In Re the Marriage of: Mary E. Frendin, petitioner, Respondent, vs. Steve Frendin, Appellant.

may not be cited except as provided by

Minn. Stat. §480 A. 08, subd. 3 (1996).

 STATE OF MINNESOTA

 IN COURT OF APPEALS

 C7-98-838

In Re the Marriage of:

Mary E. Frendin, petitioner,

Respondent,

vs.

Steve Frendin,

Appellant.

 Filed December 8, 1998

 Affirmed

 Anderson, Judge

Polk County District Court

File No. F8-95-620

Mary E. Seaworth, Howe & Seaworth, 421 DeMers Avenue, Grand Forks, ND 58201 (for respondent)

Steve Frendin, 433 Central Avenue, Crookston, MN 56716 (appellant pro se)

Considered and decided by Toussaint, Chief Judge, Anderson, Judge, and Mulally, Judge.[*]

 U N P U B L I S H E D O P I N I O N

 ANDERSON, Judge

Appellant challenges the district court's 1) valuation of a 401(k) plan; 2) denial of his motion for the termination of the reservation of spousal maintenance; 3) denial of his motion for transfer of personal property; and 4) denial of his motion to reestablish "college accounts." Because we see no abuse of discretion or error in the trial court's decisions, we affirm.

 FACTS

Appellant Steven Frendin and respondent Mary E. Frendin were divorced in January 1996 and a judgment was entered dividing the parties' property and reserving the issue of spousal maintenance. The parties were each awarded an undivided 50% interest in appellant's 401(k) pension plan. Among the assets at issue in the dissolution were certain accounts maintained by Piper Jaffray, also known as "college accounts." Those accounts, established in the names of the children of the parties, were determined to be respondent's non-marital property because they were established through funds she received by inheritance. Appellant's challenge to the dissolution judgment was rejected and this court affirmed the underlying judgment. See Frendin v. Frendin, No. C5-96-476, 1996 WL 589066 (Minn. App. Oct. 15, 1996).

Respondent filed a motion in district court on August 28, 1997, requesting appellant to account fully for his 401(k) plan and find appellant in contempt for disregarding the provisions of the judgment regarding the 401(k) plan. In his response, appellant 1) asserted that the district court made numerous mistakes in the division of property between the parties; 2) requested that respondent provide him with informational access to the Piper Jaffray accounts; 3) argued that items of property awarded to him were never transferred; and 4) requested that the issue of spousal maintenance be resolved.

After determining that appellant had closed out his 401(k) plan and that he had failed to pay respondent, the district court found appellant in contempt of court for failure to comply with the judgment. The district court, based on the absence of any evidence offered by appellant, denied the request to terminate the reservation of spousal maintenance. The court concluded that the property disposition set forth in the judgment and decree is the law of the case and cannot be altered or modified by the district court.

The district court also determined the value of the 401(k) account and ordered appellant to pay respondent her interest in the account. Appellant now appeals the district court's order 1) valuing the 401(k) account; 2) denying appellant's motion for termination of the reservation of spousal maintenance; 3) denying appellant's motion for transfer of specifically listed personal property; and 4) denying appellant's motion to reestablish "college accounts."

 D E C I S I O N

 I.

Respondent argues that appellant is precluded from challenging the valuation of the 401(k) account because appellant failed to timely appeal the December 23, 1997, order valuing the 401(k) account. In marital dissolution actions, an appeal from an order may be taken within 30 days after an adverse party serves written notice of filing. Minn. R. Civ. App. P. 104.04, subd. 1. At a minimum, the notice of filing must state what has been filed and when. Rieman v. Joubert, 376 N.W.2d 681, 684 (Minn. 1985). Respondent's notice of filing states that the order was dated December 23, 1997, and that it was filed with the district court clerk, but the notice does not indicate the date the order was filed. The order was filed on December 24, 1997. Because respondent's notice does not indicate when the order was filed, it is not an effective notice of filing and did not limit the time to appeal the order. See Garcia v. Commissioner of Pub. Safety, 572 N.W.2d 311, 313 (Minn. App. 1997) (service of letter that does not contain minimum elements for notice of filing, including date of filing, does not limit appeal time).

 II.

An appellate court will not reverse a trial court's valuation of an asset unless it is "clearly erroneous on the record as a whole." Hertz v. Hertz, 304 Minn. 144, 145, 229 N.W.2d 42, 44 (1975). An appellate court does not require the trial court to be exact in its valuation of assets; "it is only necessary that the value arrived at lies within a reasonable range of figures." Johnson v. Johnson, 277 N.W.2d 208, 211 (Minn. 1979) (citing Hertz, 304 Minn. at 145, 229 N.W.2d at 44).

Appellant challenges the district court's valuation of the 401(k) account. Error, however, is never presumed on appeal. White v. Minnesota Dep't of Natural Resources, 567 N.W.2d 724, 734 (Minn. App. 1997) (quoting Midway Ctr. Assocs. v. Midway Ctr. Inc., 306 Minn. 352, 356, 237 N.W.2d 76, 78 (1975)), review denied (Minn. Oct 31, 1997). Appellant points to no evidence in the record indicating that the court erred. Therefore, we affirm the district court's valuation of the account.

 III.

"The standard of review on appeal from a trial court's determination of a maintenance award is whether the trial court abused the wide discretion accorded to it." Erlandson v. Erlandson, 318 N.W.2d 36, 38 (Minn. 1982). A maintenance award may be modified only upon clear proof of facts showing a substantial change in circumstances. Wiese v. Wiese, 295 N.W.2d 371, 372 (Minn. 1980).

A movant for maintenance modification must not only demonstrate the existence of a substantial change of circumstances, but is also required to show that the change has the effect of rendering the original maintenance award both unreasonable and unfair.

 Beck v Kaplan, 566 N.W.2d 723, 726 (Minn. 1997).

Appellant did not present any evidence at the hearing to prove a change in circumstances; therefore, the district court did not abuse its discretion in denying appellant's request to cease holding the issue of spousal maintenance in reserve.

 IV.

Appellant moved to compel respondent to produce certain property he alleged he was awarded in the judgment. The district court found respondent's testimony that she did not have that property to be credible. We defer to that finding. See Sefkow v. Sefkow, 427 N.W.2d 203, 210 (Minn. 1988) (appellate courts defer to district court credibility determinations). Because the district court also ruled that some of the property appellant sought was not awarded to him in the judgment, it construed the portion of appellant's motion seeking that property to be a motion to modify the property division. See Minn. Stat. § 518.64, subd. 2 (Supp. 1997) (absent circumstances listed in Minn. Stat. § 518.145, subd. 2, property division is final). Because the judgment is clear that the property in question was not awarded to appellant and because appellant made no argument supporting a motion to modify the original property division, the district court did not abuse its discretion in denying appellant's motion. See Head v. Metropolitan Life Ins. Co., 449 N.W.2d 449, 452 (Minn. App. 1989) (stating existence of ambiguity in a dissolution judgment is legal question), review denied (Minn. Feb. 21, 1990); see also Schoepke v. Alexander Smith & Sons Carpet Co., 290 Minn. 518, 519-20, 187 N.W.2d 133, 135 (1971) (assignment of error based on "mere assertion" and not supported by argument or authority in appellant's brief is waived unless prejudicial error is obvious).

 V.

All divisions of personal property under section 518.58 are final and may be revoked or modified only pursuant to section 518.145, subd. 2. Minn. Stat. § 518.64, subd. 2(e). The Piper Jaffray accounts were determined in the original judgment to be respondent's non-marital property. Although appellant appealed that judgment to this court in 1996, he did not appeal the determination that the Piper Jaffray accounts were non-marital. See Frendin, 1996 WL 589066 at *1. The determinations made in an appealable order are final after the time for appeal has expired which is the situation here. Dieseth v. Calder Mfg. Co., 275 Minn. 365, 370-71, 147 N.W.2d 100, 103 (1966).

Finally, appellant requests that this court order the trial court's contempt order of September 25, 1997, permanently stayed. Appellant provided no argument or support for this request. Issues not briefed on appeal are waived. Melina v. Chaplin, 327 N.W.2d 19, 20 (Minn. 1982).

Affirmed.

[*]Retired judge of the district court, serving as judge of the Minnesota Court of Appeals pursuant to Minn. Const. art. VI, § 10.