I don't understand, sorry. I reviewed the third post from the link you forwarded but it didn't seem to fit exactly what I am (trying) to do. My problem is that nothing happens (no columns hide/unhide) when the content (text, not numerical values) of the cell linked to a ComboBox changes (when a different listing in that Combobox is selected.) If I double click in the linked cell and then double click in any other cell, then the hiding/unhiding works. Specifically, what am I doing wrong with my code, please?

I'm sure this is a very basic question but I've searched for several hours online and have found nothing that works. I'm very frustrated...

Thanks for your help. David