Unable to select repair option iPhone 3G

I am attempting to send in my iPhone for repair, so I am going through the steps (describing the issue, etc.) It then comes to the 3rd step for Additional Information and asks If Apple determines that the product is ineligible for covered service, tell us how you would like to proceed and your options are return my product without service or I will pay for the service. I am not able to select I will pay for the service, is there a reason why?
iPhone 3GS iOS 4