                             Appellant next contends that the district court committed
                 reversible error by admitting an audio recording of a conversation between
                 appellant and one of the minor children. Appellant argues that the
                 recording was not authenticated or disclosed to him before trial. The
                 record indicates that appellant did not object to admitting the recording so
                 long as he was given an opportunity to listen to it at the conclusion of the
                 proceeding. The district court noted in its order that a copy of the
                 recording was mailed to appellant shortly after the hearing. Thus, by
                 failing to object, appellant waived this issue on appeal. See Wolff u. Wolff,
                 112 Nev. 1355, 1363-64, 929 P.2d 916, 921 (1996) (holding that an
                 argument or objection not raised below is waived on appeal).
                             Appellant further contends that the district court improperly
                 admitted text messages relating to settlement negotiations over his
                 objection. Appellant failed to include the text messages in the joint
                 appendix. While the text messages were discussed at the hearing to a
                 limited extent, we cannot determine their exact content and whether they
                 related to any settlement discussions. Appellant bears the burden of
                 creating an adequate appellate record, and his failure to do so leaves this
                 court unable to adequately evaluate his argument.         Carson Ready Mix,

                 Inc. v. First Nat'l. Bank of Nev., 97 Nev. 474, 476, 635 P.2d 276, 277
                 (1981).
                              Finally, appellant contends that the district court abused its
                 discretion in failing to divide the parties' property interests. The district
                 court declined to decide the property issues, stating that it lacked subject
                 matter jurisdiction. We conclude that the district court had jurisdiction to
                 decide the property issues under Landreth v. Malik, 127 Nev. 251
                 P.3d 163 (2011). In Landreth, this court held that district court judges

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                sitting in family court have the authority to hear property matters
                between unmarried parties. Id. at , 251 P.3d at 166-67. Additionally,
                the Ninth Judicial District Court is a court of general jurisdiction, which
                has original jurisdiction in all cases outside the jurisdiction of justice
                courts. See Nev. Const. art. 6, § 6(1); NRS 3.019 (requiring two judges in
                the Ninth Judicial District); NRS 3.0105(1) (establishing family courts in
                judicial districts with populations exceeding 100,000 persons); Landreth,
                127 Nev. at , 251 P.3d at. 170 (discussing the general jurisdiction of
                district courts in jurisdictions without family courts).
                            The issue of subject matter jurisdiction may be raised at any
                time and by this court sua sponte. Landreth, 127 Nev. at , 251 P.3d at
                166. While we acknowledge that judicial estoppel may apply in this case
                because appellant took the opposite position below by arguing that the
                court lacked subject matter jurisdiction over all property issues, it is a
                discretionary doctrine. Mainor v. Nault, 120 Nev. 750, 765, 101 P.3d 308,
                318 (2004). Here, the considerations of judicial estoppel do not outweigh
                the considerations of judicial economy. To hold otherwise would cause a
                court of general jurisdiction to consider multiple cases where one would
                suffice. In the interest of judicial economy, we conclude that respondent's
                counterclaim for property division should be resolved in the underlying
                proceeding. Cnty. of Clark, ex rel. Univ. Med. Ctr. v. Upchurch, 114 Nev.
                749, 752-53, 961 P.2d 754, 756-57 (1998) (noting that judicial economy is
                an important consideration in the litigation process).
                             Accordingly, we reverse the portion of the district court's order
                declining to resolve the property issues and we remand this matter to the
                district court for further proceedings relating to respondent's counterclaim



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                  for property division. We affirm the district court's order in all other
                  respects.
                              It is so ORDERED.




                                                             Hardesty


                                                                 Z/1774'                  , J.
                                                             Douglas

                  CHERRY, J., dissenting:
                              I cannot agree with my colleagues on the property issues.
                  While the district court had subject matter jurisdiction to resolve the
                  property issues, appellant is estopped from asserting this argument
                  because he successfully asserted the opposite position below. This court
                  may invoke judicial estoppel when: (1) a party takes two positions; (2) in
                  judicial proceedings; (3) the party successfully asserted the first position;
                  (4) the positions are inconsistent, and (5) the first position did not result
                  from ignorance, fraud, or mistake.    Mainor v. Nault, 120 Nev. 750, 765,
                  101 P.3d 308, 318(2004) (noting that judicial estoppel is discretionary and
                  intended to protect the court's integrity). The appellate record indicates
                  that respondent filed a counterclaim in which she sought to divide the
                  parties' property, and in his answer to her counterclaim, appellant
                  specifically asserted that the district court lacked jurisdiction to hear any
                  issues relating to personal or business property. The district court agreed
                  with appellant and dismissed respondent's property claims. Appellant's
                  position that the district court lacked jurisdiction was intentional, as he
                  admitted that he intended to file a separate action to partition omitted

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                 property. See Arnie v. Arnie, 106 Nev. 541, 542, 796 P.2d 233, 234 (1990).
                 Appellant's argument on appeal that the district court indeed had
                 jurisdiction to divide property is precluded by judicial estoppel. Thus, I
                 would affirm the district court's order, and for that reason, I respectfully
                 dissent.


                                                                                         ,   J.




                 cc: Ninth Judicial District Court Department 1
                       Shawn B. Meador, Settlement Judge
                       Mills & Mills
                       Jamie C. Henry
                       Douglas County Clerk




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