Hi Davej,
So incredible silly of me! I have searched the document several times for any other "echo" or "print" without success, so I assumed that the echo above was the reason for the printed zero. But now I realised it was just a simple "0" that slipped in to the code :-S
Thanks for pointing me in the right direction!
But, I'm still curious about the "echo" in the form tag. Why is it needed and what does it do?