Help with water leak

To clarify, this window is on a slide. When I took it to the dealer (twice for the leak), I showed them where it was leaking on the window and showed him the valance that was getting wet. You could see the stains in the material on the valance. The first time they worked on it, they caulked around the window and took out the screws that hold the slide topper on and put calk on screws and put them back in. The slide topper screws are near the valance. The 2nd time they worked on it they put a piece of tape along the inside top of the slide, but not out at the end where the window is. I didn't understand why because that is not where the leak is. The leak can't be coming from the roof since this is on a slide that sticks out 22 inches or so. I didn't see anyplace on top of the slide where water could be coming in so I am stumped. I hate to keep throwing money at the dealer but I don't want to get water damage due to the leak. It doesn't leak every time it rains and this time the valance over the widow didn't seem wet.