There are a bunch of threads from people with this issue, check that your SSN (if you're in the US) is entered in your payment settings and also any tax forms etc. have been sent to Zazzle. Some people have found that their SSN needed to be re-entered - even if it's there perhaps you could try re-entering it and clicking 'Update'.
I'll have a look for some of those other threads.

Steve.

EDIT: Here's one; http://forum.zazzle.com/basic/anyone_else_missing_a_march_payment