Fiberglass and Rubber Adhesive

[glav]

Hello to all and Happy New Year!! I have a question for the group.

I am looking for a good adhesive to seal Rubber gasket to a fiberglass slide out. Unfortunately my trailer has a exterior rubber gasket that is attached over the edge of the slide out and goes all around the circumference of the slide. I had to replace the rubber gasket now three times (very poor design). I have used silicon rubber sealant and adhesives. They do not work! The bond to the rubber will not hold. After a very short time the seal breaks down and comes apart. I once found some butyl rubber compound in a tube and that stuff really worked good. But the problem is that I cannot find that material any more. I have attached some pictures of the latest attempt to secure the rubber gasket, but I am not optomistic this will hold up for very long. So if anybody has a good adhesive I would appreciate it very much if you share that infomation with me.
Thanks
Gene