Null value in combo box - 'Cannot assign a null value to a variable'

[hjgwright]

Hi.
I get the 'Cannot assign a null value to a variable' error when I enter a new name in my 'company' (company name) combo. I have some info on creating a null value in a combo, but I don't think it worked for me.

What I need to do is allow users to enter an unknown company in the combo, which triggers the NotInList event (which I've done - this is set to open up the Company Form). This works as long as the user leaves their 'unknown' company in the field. If they delete it (and render it 'Null') I just get an error (at the top) and it won't open up the Company form etc.

Anyone know how to get around this please?

Thanks,
HW