asp.net app javascript popup window doesn't display
<p>My imagebutton will not cause the popup window to appear when its clicked. Here is my code. </p>

<pre><code>&lt;html xmlns="http://www.w3.org/1999/xhtml"&gt;
&lt;head runat="server"&gt;
&lt;script type="text/javascript"&gt;
    function goToAddNewsletterAddPage() 
    {
        window.open("Newsletter.aspx","mywindow");
    }
&lt;/script&gt;

    &lt;asp:Image ID="Image1" runat="server" Height="87px" Width="158px" ImageUrl="~/images/signup.gif" onclick="goToAddNewsletterAddPage()"/&gt;
</code></pre>
