as stated below, new members can only unlock PM functionalities by being active for atleast 24 hours and being actively engaged in the community and posting a certain amount of times. see below.
New Members:
How can I create a thread, send a PM to a user, or join the chat?
The permissions to create a thread, send and receive PMs, and to use the chatroom will be granted automatically after you post a certain secret number of times and are active for at least 24 hours. This is to avoid spam and abuse of accounts. Please see Rules & Info for further information.