shareing acess problem

hi to all,
i am working on 50 PC’s network. some PC’s has win2000 & some has win98 & 95. I am able to acess win98 & 95 pC’s sheared C drive & D drive from win2000 but from win98 & 95 PC’s i am not able to acess win2000 PC’s share C & D drive, All PC’s are in one workgroup and using NETBUei & TCP/IP
in network properties.
want some solution