Thank you for all your remarks.

The END statement was there only for testing purpose; I'm going to remove it.

Yes, Pbtn=9 if no button is pressed.

Well Paul, I think you have found the problem.

Regarding the "IF xxxx THEN yyyy : zzzz", I thought that the "zzzz" would be executed ONLY when the IF statement is true. This is why I wrote it after each IF statement (didn't check this out now - will do this in a few minutes).

I'll come back asap.