Problem with radio buttons in a repeater

I can use the asp control and find the radio buttun in the code behind when a button is clicked but the user can select multiple buttons, or I can use an html input type radio and be able to select only one button of the group but not find it in the button's click event.  Is there a way to both be able to find the radio button AND have it di what it's supposed to - only allow one to be checked?

...