Broadband Wireless connection

I’m in Madagascar and I need help with my Internet connection. I can’t get access to the Net with linux and I’m using a Broadband Wireless connection (I’m linked with my ISP with antenna.)

Parameters are correct (IP, Mask, DNS) but connection doesn’t work with any linux distros (FC2, KNOPPIX, Mandriva, etc.) ; with windows XP, there’s no problem.

Thanx for your help !