To me, it is much easier to simply bind the option group to the field you want updated. Make sure that the wizard wand is clicked and add an option group to your form:
1. Fill in the labels you want (Full Time, Part Time, etc).
2. Choose a default value, if you want one.
3. Fill in the values you want. These are automatically assigned by Access as 1,2,3, etc in the order that you entered the labels, but you can change them to any other numbers: 5,1,307, if it suits. You will not be able to use text values.
4. Choose 'Store the value in this field' and select the field you want to store the values you assigned at (3) above, that is, the bound field.
5. Choose a style for your buttons.
6. Name the control.
And there you are.