Can't find Gem

I recently installed ruby 1.8.7 and rubygems 1.3.5. Right now i’m trying
to use the ruby-debug gem, but when i

script/server --debugger

i get the error:

You need to install ruby-debug to run the server in debugging mode. With
gems, use ‘gem install ruby-debug’

Even after I have run sudo gem install ruby-debug multiple times. So i
checked my gem environment:

RubyGems Environment:

I checke in /usr/local/lib/ruby/gems/1.8 and sure enough i have
ruby-debug correctly installed but still not recognized when i try to
start my server. I also added this to my .bashrc to make sure:

export GEM_HOME=/usr/local/lib/ruby/gems/1.8
export GEM_PATH=/usr/local/lib/ruby/gems/1.8

Even so, i’m still stuck. I’m fairly certain i’ve got multiple versions
of rubygems. Even so on the surface it looks like everything is setup
and in its correct place, but still not working. Does anyone have any
additional commands or troubleshooting i can run?