What phone are you using? And what files did you flash on it.

Here's the step I would take to troubleshoot the problem.
-If you are texting MMS, you should double check your MMS settings from your carrier.
-If the above doesn't work, I would remove battery, reinsert, and reboot the phone.
-If all else fails, do a reflash of main, fs, and custom. Make sure you are using the right ones though.