Why can't I join a paid contest?
There are generally two reasons why you might not be able to join a paid contest:
You do not have enough funds to pay for the contest entry fee. You can check your account balance by clicking the menu in the top-right corner and choosing Profile -> Account Balance. In addition to your balance, there is also a link provided to Add Funds if you need to transfer funds to your account.
You do not have the appropriate Age and Eligibility settings. You can check your settings by clicking the menu in the top-right corner and choosing Profile -> Age and Eligibility. Follow the instructions there to update your settings appropriately.