Just tried again and still not gettting any joy. This time it's a simpler document and it redirects to done.php, but it's not even doing that. So I can only conclude that there is some sort of minimum criteria to be met to submit... but I haven't set any. The only field I'm trying to update is the quantity filed, but it's just not happening. No update to amounts and no redirect on button press.
Another file is attached for you.