Trouble joining "Insider"?

I finally decided to join "Insider" on this site (thanks to the 50% off program). I'm looking forward to using the Audio Bluebook. In any case, I keep getting the message (in red) that my zip code validation failed. I updated my profile and credit card info last week, but still no membership. I'm starting this thread to see if others have had this problem, or if I'm doing something wrong please point it out. The directions on the email I received said, "Choose Pay Annually, add the code A50, press Join." Certainly sounds easy.