pop up auto close after button click event--asp.net

[yongwc2710]

 <script type="text/javascript" src="../js/showModalDialog.js"></script>        

<script type="text/javascript"> function AdminshowAssignSold() { var answer = window.showModalDialog("AssignSold.aspx?ProID=<%=Request.QueryString("id") %>",null, "dialogWidth:500px; dialogHeight:500px; center:yes"); answer.focus(); if (answer == "1") location.reload(); } </script>

Please assist on this . the pop up windows close automatically after finishing the click event from parent page :
<asp:Button ID="btnSold" runat="server" Text="Mark as SOLD" CausesValidation="False" />
vb.net:
btnSold.Attributes.Add("onClick", "AdminshowAssignSold();")

[mrwoodo]

Same as #9 Problem with pages .aspx, have added example workaround