>Hi,
> I have a top level form and multiple MDI form. I place toolbar on my top level form and issue _SCREEN.ACTIVEFORM.mymethod(). It works most of the time, but VFP give error ACTIVEFORM is not an Object sometime... why does it happen? hor to solve?
>
>Thank you

Sometimes, there is no ActiveForm at that time. It's safer to look for the form you really need, and use its reference to call the method, e.g.

For Each oForm in _SCREEN.Forms
 If oForm.Name=="MyForm"
  oForm.mymethod()
  Exit
 Endif
Endfor