This could be for any number of reasons. The common answers are as follows:
Have you validated your account? To do this you must click the link sent to you via email when you joined up. Emails usually take around 24 hours to arrive. Be sure to check any "Spam" or "Junk Mail" filters you may have active on your account. If you have not activated your account within 28 days, your registration information will deleted and you will need to re-join. If you cannot find your email or wish it be resent, please contact an Administrator. If you have completed the email activation an Administrator will need to approve your membership request. This is usually done within 48 hours, although there can sometimes be a delay. Please be patient! If you have not heard within 5 working days, please contact an Administrator for assistance.