Rspec Controller test failed with Factory_girl "Should be stubbed / mocked under test"

I am testing a controller with rspec and I get the error message "Should be stubbed / mocked under test" (and don't find any result on google)

I am using a factory_girl to create an object that I am using without any problem when testing my models. I am only getting the error when I am calling "FactoryGirl.create" and not for "FactoryGirl.build"

can anyone give me hint what my problem is or how I can solve the problem?