No tabbing after setFocus

I have a form where I place the cursor in the first dynamic text field using

Selection.setFocus(nameField);

This works fine, except that hitting the tab key will not move the cursor to the next dynamic text field (in this case, companyField).

I tried

companyField.tabIndex = 1;

and

companyField.tabIndex = 1;

but neither works.

Is there a way to use the setFocus statement and still enable tabbing?

Thanks.