IPhone 4 not texting pictures?

I just switched to iPhone 4. On my old phone I was able to send pictures and I don't believe my parents changed our phone plan since. I'm able to get on internet when not in Wi-Fi. Whenever I try to send a text that's not an iMessage and I try to press the little camera icon to the left of the box where you type the message i keep pushing it but never does anything. It won't even let me add a picture to the text. I have tried resetting network settings, turning cellular on and off in settings, what could be the problem?

Have you tried rebooting? Try to reboot several times, it worked for me after a few times. If isn't doesn't make an appointment with the Genius Bar at apple.com