Juan,
I just dropped 3 textboxes and a timer on a form. Put this Timer() method in:
debugout thisform.ActiveControl.Name
It works quite fine, as long as the form has focus. If you click on the command window for example the form loses focus and the references error out like you are seeing. So what is taking focus away from your form?
If you code it like:
if ( type( "thisform.ActiveControl.Name" ) != "U" )
debugout thisform.ActiveControl.Name
endif
It at least won't error out when the form does not have focus. You might try turning on event logging to get a handle on what events are firing when it doesn't work.
>I am checking for the ActiveControl in a Timer.Timer Event. And yes, the timer is part of the form that I reference.