help with at&t aircard and macbook pro

I need help with an at&t aircard sold to my client for his macbook pro. I have installed the GlobeTrotter Connect software for the aircard as instructed by at&t. The software finds at&t's network and even shows 3-4 signal bars. When I click connect, no dice! It says check network settings. at&t says they don't support the macbook. I have searched online and found only dead threads with useless links to software that does not work. If anybody has any information (no matter what) about this set up, please respond. Thank you ahead of time.