.net - Why Won't The ModalPopupExtender Show / ASP.NET And JavaScript

I'm trying to call a modal popup extender from javascript. Here's the call:

function MyFunction()
{alert("test");
$find('mdlPassword').show;}

I get the alert when it's called, but the modal popup extender won't show. Here's the aspx stuff:

<!-- Popup Extenders Should Go Here -->
<asp:button id="Button1" runat="server" text="Button" style="display: none;" />
<asp:ModalPopupExtender ID="mdlPassword" runat="server"

[code]....