Issue with Tab order in UDO

Experts help to solve this problem

I have create a table  "ABC" and I register the udo its show code(1),name(2),add(3),cancle(4) that's ok

but when I tab out from name(2) its set focus on add(3) and its looping between add(3) and canle(4).that ok.

But when I create new table "XYZ" and I register uod , and when I tab out form name(2) its set focus on code(1), and its looping between(1) and (2) its behavior is different in both the udo

please let me know the standard way of udo tab order.