<link type="text/css" rel="stylesheet" href="scripts/jquery-ui-1.8.5.custom.css" /> 
        <script src="Scripts/jquery-1.4.2.js" type="text/javascript"></script>
        <script type="text/javascript" src="scripts/jquery-ui-1.8.5.custom.min.js"></script> 
     <script type="text/javascript"> 
     function getalert1(Leave_RegisterID) 
            {
                document.getElementById('<%= hdnLeave_RegID.ClientID %>').value = Leave_RegisterID;
                $.fx.speeds._default = 1000;
                $(function () {
                    $('#reason').dialog({
                        autoOpen: false,
                        show: "blind",
                        hide: "explode",
                        display: ''
                    });
                    $('.LeaveReason1').click(function () 
                    {
                        $('#reason').html();
                        $('#reason').dialog('open');
                        return false;
                    });
                });
            }
</script>
私がクリックするボタン:
      <button id="LeaveReason1" class="LeaveReason1" onclick="getalert1('<%# Eval("Leave_RegisterID") %>');" title="Decline">Decline</button>
ただし、firebugでデバッグすると、次のコード内に入らないはずです:
   $('#reason').html();
   $('#reason').dialog('open');
   return false;
HTML
 <div id="reason" style="height: 300px; min-height: 109px; width: auto; display:none;" class="ui-dialog-content ui-widget-content"   runat="server">   
            <table width="100%" border="0" cellspacing="0" cellpadding="0">  
                <tr>
                    <td width="25%" class="body_txt" style="padding-right:2px">
                        <asp:Label ID="lblReason" runat="server" Text="Reason:" ></asp:Label>
                    </td>
                    <td width="75%">
                        <asp:TextBox ID="txtReason" Height="40%" Width="100%" MaxLength="200" TextMode="MultiLine" runat="server" CssClass="txt_bx" ></asp:TextBox>
                    </td>
                </tr>
                <tr>
                    <td colspan="2"> </td>
                </tr>                    
                <tr>
                    <td colspan="2" align="center">
                        <asp:Button Width="30%" runat="server" Text="Submit" id="btnSubmit" Height="25px" CssClass="clButton" ></asp:Button>   
                    </td>
                </tr>
            </table>
        </div>