redmine_ active record relationship

redmine_active_record_relationship

#in my communication.rb file, I have added following code

class Communication < ActiveRecord::Base
  unloadable
  belongs_to :user


  User.class_eval do
    has_many :communications
  end

end

#in my communications_controller.rb file
def index
    @messages = Communication.find(:first)
end

#in index.html.erb (here I can able to take the user name from the message object)
	<%for message in @messages %>
                     <div style="padding-bottom:5px;float:left;width: 70%;">
                        <%= message.user.name  %> 
                      </div>
        <% end %>

#i got the following error
undefined method `name' for nil:NilClass