u can see When you are Signing Up they wants Domain On Example.blogspot.com this is not called Proper Domain its called Sub Domain ... u have to Own a Personal Domain Than Try never Decline you... Hop it would be Your answer
Is your blog at least 6 months old? Does your blog meet all the requirements of the Program Policies? (Have you read the Program Policies?) Does your blog have substantial original content? Lots of people get approved using example.blogspot.com addresses, as long as their blogs meet the rquirements.