Yes/ No Fields in forms

I created a new custom field for a form that can only have a yes or no answer when used on a form. When i try to tag the lead so that i can see if the answer was yes or no on both the customer confirmation email and the alert to staff, I am having trouble getting the answer NO to appear. I tried making the custom field a Boolean and then tried by making it a text field, but if i select either radio buttons or check boxes in the form for the yes and no answers, only the YES appear in the results, the NO appears blank.

Anyone know what i am doing wrong? i am very new to Marketo.

Thanks, Lisa