Error in loading WEBrick server

Hello ... I am new in ruby on rails, I installed MYSQL2 gem and it gave
me message that It is installed successfully.

When I try to run (rails s) on new application with MYSQL DB..it gives
me the next errors and didn't run

C:\Sites\Simple_CMS>rails s
C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/bundler-1.7.7/lib/bundler/lockfile_parser.rb:91:in
`parse_source': undefined method `[]' for nil:NilClass (NoMethodError)
        from
C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/bundler-1.7.7/lib/bundler/lockfile_parser.rb:45:in
`block in initialize'
        from
C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/bundler-1.7.7/lib/bundler/lockfile_parser.rb:39:in
`each'
        from
C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/bundler-1.7.7/lib/bundler/lockfile_parser.rb:39:in
`initialize'
        from
C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/bundler-1.7.7/lib/bundler/definition.rb:57:in
`new'
        from
C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/bundler-1.7.7/lib/bundler/definition.rb:57:in
`initialize'
        from
C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/bundler-1.7.7/lib/bundler/dsl.rb:152:in
`new'
        from
C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/bundler-1.7.7/lib/bundler/dsl.rb:152:in
`to_definition'
        from
C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/bundler-1.7.7/lib/bundler/dsl.rb:11:in
`evaluate'
        from
C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/bundler-1.7.7/lib/bundler/definition.rb:25:in
`build'
        from
C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/bundler-1.7.7/lib/bundler.rb:154:in
`definition'
        from
C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/bundler-1.7.7/lib/bundler.rb:117:in
`setup'
        from
C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/bundler-1.7.7/lib/bundler/setup.rb:7:in
`<top (required)>'
        from
C:/RailsInstaller/Ruby2.1.0/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:128:in
`require'
        from
C:/RailsInstaller/Ruby2.1.0/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:128:in
`rescue in require'
        from
C:/RailsInstaller/Ruby2.1.0/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:39:in
`require'
        from C:/Sites/Simple_CMS/config/boot.rb:4:in `<top (required)>'
        from bin/rails:3:in `require_relative'
        from bin/rails:3:in `<main>'

BUT ... If i tried to run the server on different application that I
made before and that application is using sqllite DB, the server is
running with no errors !!!!

any suggestions ??

Can you show us your Gemfile? And also the output of running "bundle install"?