Only one checkbox true in a group

[etb1025]

I have a user form with two groups of checkboxes. The first contains 8 (11, 7, 8, 9, 12, 13, 14, 15) and the second contains 4 (21, 20, 19, 17). They are form control check boxes. I only want on checkbox allowed to be checked in each group.

 

[etb1025]

I have a user form with two groups of checkboxes. The first contains 8 (11, 7, 8, 9, 12, 13, 14, 15) and the second contains 4 (21, 20, 19, 17). They are form control check boxes. I only want on checkbox allowed to be checked in each group.

Oh, and they are on sheet 3