NULLs w/ verify lookup join in perform?

We have created a form using perform which uses codes from several other tables as entries in the active table. We have used a verify lookup join to allow only those codes which are present in the other table. Our problem is, if the user wants to remove the code or accidentally starts typing where they really wanted a null, the form will not allow a null entry. It keeps saying that the null value does not exist in the other table. We have tried adding a null entry to the codes table and even an entry with all spaces but nothing seems to work...Our form will simply NOT allow a null entry once a character has been entered into the field. (If you press <Return> to skip past the field it works fine - just not if something has been entered) Does anyone have any ideas on how to make this work? (That is...allowing the user to erase a code and leave a blank or recover from a mistake without aborting and starting the update all over???) Any and all help will be greatly appreciated!! Thanks in advance. "Lancinator" lmc@hpdmd48.boi.hp.com