Hi Matthias,
Sorry, but I'm not "halfway true". It means that something in your form definition or your code prevent B1 to correctly change the form's Mode
Saying this: may you check the AffectFormMode property of all items in the form and sets it to false (0 in the srf file) when it is not relevant (i.e; all buttons, all static text, the Matrix object, etc.)?
Regards,
Eric