Form Controls and Data Validation for Excel on a Mac

Hi All

I'm trying to put a form control combo boxes and data validation in various cells of a spreadsheet. Unfortunately, users with Macs cab see the combo boxes and data validation cells, they can select the drop down arrows and see the selections, but when they want to click on any of the selections it will not transfer it to the cell. Is there any configuration settings I have to do in the excel program for macs

ANY HELP WOULD BE GREAT!!!

Cheers!