I was doing it wrong all together.
first I needed to say this in the Init()
DO CASE
CASE .opgroup.option1.Value = 1
thisForm.myProp = 'A'
CASE .opgroup.option2.Value= 2
ThisForm.myProp = 'B'
ENDCASE
and then I made the mistake of setting the control source to 'A' and 'B'...and I did not need that.
now is good.

Thank you