MOBILE NOT DETECTED BY SERVER

Hi! experts,
I am an owner of Nokia 6100 phone, whose firmware version is 5.5, npl-2 Nokia. I am not able to connect my mobile to my server on which I installed redhat Linux 7.0 using Nokia dku-5 cable. My operating system is detecting cable. If I am setting up values of parameters to dku-5, its giving me unsupported connection dku-5. For other cables the software is unable to detect my mobile. I tried gnokii version 0.5 & 0.6, but its not getting connected. I have tried this connection in windows XP which is working fine with my cable. Is there any idea why my server is not detecting this cable for gnokii?. Waiting for reply!
Thank you.
