When using form objects on your page, the order in which you place the objects controls the tab sequence when the page is previewed/published. If you move the objects to new positions, the tab sequence may no longer appear logical. In this case, you can re-align the tab sequence by resetting the z-order of the objects.
Another method is to use the tabindex attribute of the objects so the tab sequence is maintained no matter where you move the objects. This is done by add the code:
tabindex="N"
to the form object Code field, where N is a number, starting at "1" and incrementing by one for each successive form object.