我的rspec测试不会通过：Michael Hartl的rails教程

require \'spec_helper\'

describe \"LayoutLinks\" do

    it \"should have the right links on the layout\" do
        visit root_path
        click_link \"About\"
        response.should have_selector(\'title\', :content => \"About\")
        click_link \"Home\"
        response.should have_selector(\'title\', :content => \"Home\")
        click_link \"Help\"
        response.should have_selector(\'title\', :content => \"Help\")
        click_link \"Contact\"
        response.should have_selector(\'title\', :content => \"Contact\")
        click_link \"Sign up now!\"
        response.should have_selector(\'title\', :content => \"Sign up\")
        end
        end

Failures:

  1) LayoutLinks should have the right links on the layout
     Failure/Error: click_link \"Sign up now!\"
     Webrat::NotFoundError:
       Could not find link with text or title or id \"Sign up now!\"