>>>>>Does any control have TabStop property set to false ?
>>>>
>>>>Yes - I have some several fields set this way (command buttons, etc.)
>>>
>>>Could it be related to your problem? Copy this not working form and on the copy make all controls TabStop property set to true (or should it be false?) and re-test.
>>
>>
>>That doesn't seem to work either. For what it's worth, when I tab off a field, it is executing the lostfocus logic.
>
>It should - that's OK. Do you have anything in LostFocus preventing the focus to move (NODEFAULT) ?

Well - I found the problem. After removing every method, property, object (almost) to narrow down the problem, I went back to check the properties of the remaining 3 objects.

I had checked the properties of all the form objects, but did not check the form properties. It turns out that the 'Tabstop' property on the FORM was .F.. This must have been accidentally set somehow as I have never used, nor even known that there was a TABSTOP property on the Form itself. Turns off this disables / enables tabbing on the entire form.

So, hours later, I have learned something new today. Thanks very much for your suggestions.