Limey I tries that stuff man, just didn't work for me. that's what the instructions said, too. I layed the rubber down, put a little rtv over the coper and slid the tube over it. This was after trying many different ways. It still didn't work with the rtv until I put a second hose clamp of there.
I hate those suckers cause they always leak. I have a fan switch from a BMW 318i in a neat aluminium housing spliced into my top hose - neat and leak free.
If all fails try the controler from www.dccontrol.com I just got my electric setup finished in my 90' test mule and its working awsome. The controler temp probe slides into the fins of the radiator so it won't cause any leaks. It dynamically ups the fan speed according to the water temp instead of waiting for the water temp to hit a certain point then kicks the fan on resulting in a spike in your electrical system(typical electric fan draws 25-35 amps on startup) while your engine is overheating slightly before it gets it brings it down which it then turns off and does the vicious cycle again. Just a thought... Best of luck.
Kevin