how do i update the gem version from 0.9.2 to 0.9.4

hi all,
               i tried to update the gem by gem update --system but got
the error
H:\ruby_env\graph\test_ofc_2\test_ofc_2>gem update --system
Updating RubyGems...
ERROR: While executing gem ... (Gem::RemoteSourceException
    HTTP Response 302

pls tell me wt is the problem exactally.

Regards,
atul rai