I finally figured out (after taking my slide out apart) that water was running down the side of the slideout, then moving along the bottom trim on the slide out, through the rubber gaskets, and into the RV. I puttied the part of the track the water was running along - created a dam I guess. I also put eternabond over both sides of the trim.
is another post about this that might be helpful. There are lots of videos about this on youtube.