Sidekick LX saving a number help?

[Plexii]

Hi, I just got a new Sidekick LX phone. I saved my cousin's number in it and texted him but when he texted back instead of his name appearing on the New Message notification, only his number's showed up. And also I didn't see a New Message notification pop up when I got the message by the way... The phone just rang and I have to go open the Messages folder to open it. Can anyone give me any tips on this one please? ^^