SP.UI.ModalDialog.OpenPopUpPage not working in codebehind

I need to launch a InfoPath form in a Sharepoint Dialog.

Here is the Javascript:

function openInfopath(){//url = document.getElementById('TextBox1').Text;
            url ='http://devmarq/LenderDatabase/_layouts/FormServer.aspx?XmlLocation=/LenderDatabase/LenderBlog/LenderBlog-1-7.xml&ClientInstalled=true&OpenIn=Browser&DefaultItemOpen=1';
            SP.UI.ModalDialog.OpenPopUpPage(url,MyDialogCallback);}functionMyDialogCallback(dialogResult, returnValue){// Do stuff here
            alert('Dialog Closed');}

In ASP this works like a champ and displays the InfoPath form in a dialog.  Then when the dialog is closed, the alert message is displayed.
  
<a id="infoPathLink" href="#" onclick="openInfopath();return false;">Launch Infopath</a>  

However, running from codebehind, the dialog will not render:

protectedvoidOpenInfoPathForm(object sender,EventArgs e){// Call launchInfoPathForm()Page.ClientScript.RegisterStartupScript(this.Page.GetType(),"OpenInfopath","<script>openInfopath()</script>",false);}

Just to make sure I was not going crazy, I changed the javascript:

function openInfopath(){
  alert('Should Open InfoPath in a dialog');}

In both cases the alert is displayed so clearly the javascript is being executed.

Why does it not work with codebehind?

Bill Behning