Need help setting up custom multi-radio group where only one radio can be selected at a time

I have set up a multi-radio group in my form where I have several (7) options. When I first insert the multi-radio group, 3 default options were set-up. If I use just those three, I can only select one radio button at a time, which is what I want to happen. However, when I add more radio controls, I am able to select more than one buttons and two of them cannot be selected at all. I’ve made sure that the id’s for the controls are unique.