You've left out the page. Try this:

thisform.pageframe1.pagex.grid1.column3.text1.setfocus

>Command button = thisform.pageframe1.activepage=1
> thisform.pageframe1.grid1.column3.text1.setfocus
>
>I think it should work but what am I missing?
>
>When I click the command button I get a program error: Unknown member Grid1