One note - I did in the past, have problems with any WebAssist software when I chose the "any form post" as the trigger rather than "current form submit." for the eCart behavior I did choose "any form post" as you specified. But I copied the other Post behaviors as written on the confirm page. (I wrote <input type="hidden" name="CustomerID" id="CustomerID" value="<?php echo ((isset($_SESSION["eCartCheckoutForm_CustomerID"]))?$_SESSION["eCartCheckoutForm_CustomerID"]:"") ?>" />)
Instead of just the Post commands that you had advised. Could that be the source of the problems?