Error installing using rubygem

I am doing a fresh install. I have installed

OS Redhat Enterprise

Ruby 1.8.6 (from Source)

rubygems versions 1.0.1 (from Source)

when I run the following to install rails:

gem install rails --include-dependencies

I get the following error:

[root@localhost rubygems-1.0.1]# gem install rails --include-
dependencies
/usr/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in
`gem_original_require': no such file to load -- zlib (LoadError)
      from /usr/local/lib/ruby/site_ruby/1.8/rubygems/
custom_require.rb:27:in `require'
      from /usr/local/lib/ruby/site_ruby/1.8/rubygems/package.rb:10
      from /usr/local/lib/ruby/site_ruby/1.8/rubygems/
custom_require.rb:27:in `gem_original_require'
      from /usr/local/lib/ruby/site_ruby/1.8/rubygems/
custom_require.rb:27:in `require'
      from /usr/local/lib/ruby/site_ruby/1.8/rubygems/format.rb:9
      from /usr/local/lib/ruby/site_ruby/1.8/rubygems/
custom_require.rb:27:in `gem_original_require'
      from /usr/local/lib/ruby/site_ruby/1.8/rubygems/
custom_require.rb:27:in `require'
      from /usr/local/lib/ruby/site_ruby/1.8/rubygems/installer.rb:
11
       ... 11 levels...
      from /usr/local/lib/ruby/site_ruby/1.8/rubygems/
command_manager.rb:103:in `process_args'
      from /usr/local/lib/ruby/site_ruby/1.8/rubygems/
command_manager.rb:74:in `run'
      from /usr/local/lib/ruby/site_ruby/1.8/rubygems/gem_runner.rb:
39:in `run'
      from /usr/local/bin/gem:22

I have searched google up and down but cannot find a answer. Any help
will be appreciated.
-SKP

First hit: no such file to load -- zlib - Google Search

As the error says, you don't have zlib module for ruby. I guess that
you didn't have the development files for zlib installed when you
compiled ruby and the module was therefore simply not compiled and
installed. Same goes with other extensionssuch as readline, openssl,
etc.

···

On Jan 29, 9:32 pm, Sanjay Patel <sanjay.k.pa...@gmail.com> wrote:

/usr/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in
`gem_original_require': no such file to load -- zlib (LoadError)