Trouble Getting Form Submitted Through PopUp

I'm having some trouble getting a popup window form submission to work correctly. Any help would be appreciated.

Basically, I have a pretty simple setup. I have a popup window on entry to my index page. The popup works and there is a form submit button that also works ok.

The problem occurs when someone submits the form, at which point I have a behavior set up where it goes to another "thank you" page (within the same window). The problem is, I don't think the data is being submitted??

This worked without the "thank you" page. I'm thinking that the url change somehow interrupts the transfer of info.

Here's the code:

<input name="Submit" type="Submit" onClick="MM_validateForm('firstname','','R','email','','RisEmail');MM_goToURL('parent','thankyou_ebook.html') ;return document.MM_returnValue" value="Submit">

Any assistance would be greatly appreciated.....

"MM_validateForm('firstname','','R','email','','RisEmail');MM_goToURL('parent','thankyou_ebook.html') ;return document.MM_returnValue"

You need to put this under action.
<form action="">

submits don't need onClick, they do whatever action says, so it should look like this:

<form name="form1" action="MM_validateForm('firstname','','R','email','','RisEmail');MM_goToURL('parent','thankyou_ebook.html') ;return document.MM_returnValue">
<input name="Submit" type="Submit" value="Submit">
</form>

Try that.