Picture doesn't work with DB tables ?!

This probably a silly and simple question but it's really got me
stumped. I have an app with 4 tables, with fields in one being
controlled by those in the other three vi referential integrity. This
seems to work fine. I've also made some fields required - this also
works. From within the database desktop I've also stated a picture
validity check for some fields (e.g. &&*& - 2 or more capital
letters). This doesn't seem to have any effect at all and I can't see
why. Does anyone have any ideas (I think the table is Paradox 5)?

Thanks in anticipation.
Neil A. Charlton