I usually pass the form reference to the form that needs it, e.g.

do form mySecondForm with thisform

in the Second Form Init

lparameters toCalledBy

thisform.oCaller = toCalledBy

in the button's click

if vartype(thisform.oCaller) = 'O'
   thisform.oCaller.somebutton.SetFocus()
endif

>from form1 a execute form2 (CL_NEW)
>
>DO FORM CL_NEW NAME newCl
>
>From form2 a execute form 3
>
>From form 3 button.click I execute:
>newCl.ende1.setfocus
>THISFORM.RELEASE
>
>
>But is says: object not found newCl
>
>I remember have done this before
>What can be wrong ?