Class C Slide Out Leak

I never closed out this conversation. I finally found one corner on the front outer edge of the slide that seemed to be the culprit. Any time water was present on that corner, there was a leak inside. I used the recommended sealants purchased from Camping World, but even though I sealed the full length and width of the slide, water still got in if it reached that front corner. I finally replaced the slide-out topper, which worked for one season until it developed pinhole leaks again, due to wind. Right now, I'm using a workaround - a length of vinyl gutter from Home Depot. That prevents water from getting onto the slide out roof. No more leak as long as the gutter is in place.