Hi Claudio;

>In a valid of on editbox in the form1 i have:
>if condition
> opc=mymesaje("error")
> if opc = 1
> .
> .
> .
> endif
>endif
>

procedure valid
if condition
   return .f.
endif
endproc

procedure errormessage
  opc=messagebox("error")  && message box is the best tool for that purpose
  if opc = 1
     .
     .
     .
  endif
endproc

Regards

Claudio