Look in the EclipseFP "Helper executables" preferences window if it is pointing to your Hoogle installation. If not, you may click the middle button (of those three besides the text box where the Hoogle address should be) to automatically find the correct installation in your machine.
If it is not the problem, I would advise you to reformulate your question and put more information, such a screenshot of your preferences window.
Anyway, follows a example of my preference window