Rspect transactional fixture problem

I am having a problem with the following test and I cannot figure out
why. I am working through the tutorial on
and just finished chapter 9. It seems the following spec test works once
and then in order to get it to pass again I have to purge the test
database. This doesn’t seem necessary if I have transactional fixtures
enabled (which I do).

Here is the test:

   describe "success" do
     it "should make a new user" do
       lambda do
         visit signup_path
         fill_in "Name",         :with => "Example User"
         fill_in "Email",        :with => "[email protected]"
         fill_in "Password",     :with => "foobar"
         fill_in "Confirmation", :with => "foobar"
         response.should have_selector("div.flash.success", :content

=> “Welcome”)
response.should render_template(‘users/show’)
end.should change(User, :count).by(1)