Ruby on rails: - Could not find RubyGem rails (> = 0) (Gem :: LoadError)

Question

Ruby on rails: - Could not find RubyGem rails (> = 0) (Gem :: LoadError)

I am very new to Ruby on Rails. I installed ruby on rails on my Windows 7 using the installer at http://railsinstaller.org/ . I could create a project once, and then I was not (I do not know what I was doing between them :-().

Full error messages: -

When creating a new project : -

c:\Sites>rails new Tickets_Test
E:/Ashish/Ruby192/lib/ruby/1.9.1/rubygems.rb:762:in `report_activate_error': Cou
ld not find RubyGem rails (>= 0) (Gem::LoadError)
        from E:/Ashish/Ruby192/lib/ruby/1.9.1/rubygems.rb:219:in `activate'
        from E:/Ashish/Ruby192/lib/ruby/1.9.1/rubygems.rb:1065:in `gem'
        from E:/Ashish/RailsInstaller/Ruby1.8.7/bin/rails:18:in `<main>'

for version only : -

c:\Sites>rails --version
E:/Ashish/Ruby192/lib/ruby/1.9.1/rubygems.rb:762:in `report_activate_error': Cou
ld not find RubyGem rails (>= 0) (Gem::LoadError)
        from E:/Ashish/Ruby192/lib/ruby/1.9.1/rubygems.rb:219:in `activate'
        from E:/Ashish/Ruby192/lib/ruby/1.9.1/rubygems.rb:1065:in `gem'
        from E:/Ashish/RailsInstaller/Ruby1.8.7/bin/rails:18:in `<main>'

Any idea why this is happening?

EDIT

Two commands appear: - Ruby command line: - Ruby and also Ruby for rails command prompt (the problem is solved using this command line): - Ruby on rails