IsNull vs Empty vs Blank #7

Hi

Thanks for all your efforts on the sample code.

Can you guide me in the right direction, when you search for fields that are Null (IsNull) if the field has never been populated this works fine, but if you enter data in an empty field save i and then remove it, it is then not classed as null.

How do you search for a field that has no data?

Thanks,
Gary