Jquery dialog does popup if i add validation in the textbox

Hello,
I create a dialog with some validation inside. The dialog doesnt popup and it suppose to be pop up when i click on a link buttton that will trigger the code behind. But, if i remove those validations, the dialog will popup. Anyone know who to solve my problem?
Heres my dialog:
<div id="createDialog" style="display:none" > <table class="style1" id="createNewUser"> <tr> <td><asp:Label ID="siteLabel" runat="server" Text="Site:"></asp:Label></td> <td><asp:DropDownList ID="siteList" runat="server"> <asp:ListItem Text="SBOBet" Value="0"></asp:ListItem> <asp:ListItem Text="IBCBet" Value="1" Selected="True"></asp:ListItem> <asp:ListItem Text="SB188" Value="2"></asp:ListItem> <asp:ListItem Text="SLVBet" Value="3"></asp:ListItem> ...