If you can receive, but not send text messages, it may be because there is a weird "signature" on the phone, that uses characters which cricket doesn't support.
If there's a signature, try removing it, and see if it fixes the problem.
I've only ever seen this be a problem on LG phones, usually VX8500, and only a handful of times.
More likely, stevekice is right, cause lately there has been higher rate of missing features on new accounts....