Hi,
You can set the Tab Order in the "Tab Order" tab ;-) If you don't see it, you can access it from the Window menu.
The implementation of tab order varies in different versions of LC designer, so you should check the help file and serch the forums for "tab order".
Once you set the tab order, the form should work as expected. If you add new objects, you will probably have to redo the tabbing order.
Hope that helps,
N.