Redmine

I'm developing a plugin to redmine and want to create a menu on sidebar, only inside a issue.
I'm trying use on my init.rb that way:

Redmine::Plugin.register :redmine_issue_messages do
...
end

# Render the partial on side bar?!
class IssueMessagesHook < Redmine::Hook::ViewListener
    render_on :side_bar, :partial => "menu/issue_messages_menu" 
end

But don't work, anyone can help please?