Formcalc radio button

I tried the code that you suggested in a numeric field. However, I received errors.
I created unique names for the radio buttons (bttn1, bttn2, btn1a) as you had included in your code and assigned values to each button. The error I received was Script failed (language is formcalc, context is xfa[0].form[0].form1[0].#subform[0].Numericfield1[0])
script=form1.#subform[0].subform1.RadioButtonList.bttn1+form1.#subform[0].subform1.RadioButtonList.bttn2+form1.#subform[0].RadioButtonList.bttn1a
Error:accessor 'form1.#subform1.RadioButtonList.bttn1' is unknown
 
Please advise.
Thank you.