New to rails with a plugin question

Hey Everybody, i am trying to use the rails plugin ym4r_gm and nothing
i do seems to be working, and the error i am getting looks like rails
isn’t seeing the plugin.
here is the error message:
NoMethodError in Content_pages#view_default

Showing app/views/layouts/application.rhtml where line #14 raised:
You have a nil object when you didn’t expect it!
The error occurred while evaluating nil.to_html

Extracted source (around line #14):
12: <%= stylesheet_link_tag “style”, :media => “all” %>
13: <%= GMap.header %>
14: <%= @map.to_html %>

RAILS_ROOT: script/…/config/…
Application Trace | Framework Trace | Full Trace

if anybody could help me that would be awesome, i am stumped.