Redmine

Hi
I have migrated the Google Apps login plugin to redmine 1.3.0, migration process works successfully but its showing error likes this:
please help me

ActionView::TemplateError (No plugin called 'google_apps' - please use the full name of a loaded plugin.) on line #20 of app/views/layouts/base.html.erb:
17: body {behavior: url(<%= stylesheet_path "csshover.htc" >);}
18: </style>
19: <![endif]-->
20: <= call_hook :view_layouts_base_html_head >
21: <!-- page specific tags -->
22: <= yield :header_tags -%>
23: </head>

lib/redmine/hook.rb:63:in `send'
    lib/redmine/hook.rb:63:in `call_hook'
    lib/redmine/hook.rb:63:in `each'
    lib/redmine/hook.rb:63:in `call_hook'
    lib/redmine/hook.rb:60:in `tap'
    lib/redmine/hook.rb:60:in `call_hook'
    lib/redmine/hook.rb:144:in `call_hook'
    app/views/layouts/base.html.erb:20
    /usr/lib/ruby/1.8/webrick/httpserver.rb:104:in `service'
    /usr/lib/ruby/1.8/webrick/httpserver.rb:65:in `run'
    /usr/lib/ruby/1.8/webrick/server.rb:173:in `start_thread'
    /usr/lib/ruby/1.8/webrick/server.rb:162:in `start'
    /usr/lib/ruby/1.8/webrick/server.rb:162:in `start_thread'
    /usr/lib/ruby/1.8/webrick/server.rb:95:in `start'
    /usr/lib/ruby/1.8/webrick/server.rb:92:in `each'
    /usr/lib/ruby/1.8/webrick/server.rb:92:in `start'
    /usr/lib/ruby/1.8/webrick/server.rb:23:in `start'
    /usr/lib/ruby/1.8/webrick/server.rb:82:in `start'