Gravity Forms dynamic entry from URL

I’m wanting to populate a form’s multiple choice field from the url.

Fields advanced settings:
“Allow field to be populated dynamically” is checked
Parameter Name: test_q

url: http://mysite.com/form_page/?test_q=3

The form appears, but all three multiple choice responses are still blank.

Am I missing a step? I’ve been successful populating text fields from the url, but need to do the same for multiple choice and radio button fields.

Thanks in advance, RICK