Collapse Div in form

Hello,
I have a problem that I can't solve, though I dunno if it's related to Cascade or not.

I've inserted a collapse DIV in a form, but when I submit the form ($_POST) it doesn't enter into the loop to process it because the submit button is not recognized.

When I delete the DIV, the form works very well, so the collapsed/expanded DIV is the issue. 

thanks a lot.

Icha
