Rmagick error on install

i have been trying to install rmagick but have been unsuccessful.People
on Rmagick forum told me that the error is a ruby gem error, please help
.

When I typed the command “sudo gem install Rmagick” , I got the
following error::

/usr/local/lib/site_ruby/1.8/rubygems.rb:274:in initialize': wrong number of arguments (1 for 0) (ArgumentError) from /usr/local/lib/site_ruby/1.8/rubygems.rb:274:innew’
from /usr/local/lib/site_ruby/1.8/rubygems.rb:274:in configuration' from /usr/local/lib/site_ruby/1.8/rubygems.rb:520:inpath’
from /usr/local/lib/site_ruby/1.8/rubygems/source_index.rb:66:in
installed_spec_directories' from /usr/local/lib/site_ruby/1.8/rubygems/source_index.rb:56:infrom_installed_gems’
from /usr/local/lib/site_ruby/1.8/rubygems.rb:736:in source_index' from /usr/local/lib/site_ruby/1.8/rubygems/gem_path_searcher.rb:86:ininit_gemspecs’
from /usr/local/lib/site_ruby/1.8/rubygems/gem_path_searcher.rb:21:in
initialize' ... 6 levels... from /usr/local/lib/site_ruby/1.8/rubygems/gem_runner.rb:8:inrequire’
from /usr/local/lib/site_ruby/1.8/rubygems/gem_runner.rb:8
from /usr/bin/gem:10:in `require’
from /usr/bin/gem:10

Please help!!!
Thanks in advance.