Originally Posted by stopher
I think the code only needs to go in the On Current event of the form. Then it is not needed in the On Open or After Update events.
Thanks for that. Whilst this wasn't the soluction, it still errored on closing the form, it was the start of the solution. It made me rethink the logic for enabling the button.
I have now disabled the button by default, and if there are any records I activate it, rather than the other way round.