Sealing the stiching on the roof of a annex

Candle wax fills holes quite well!

If it is a NEW annexe then it will have to be wetted first so the fibres at the stitching holes become expanded and settle against the stitches. Wet all upper areas a few times so this normalization process has a chance to take effect. Also seal with the goo you have used.
Sometimes you may have to use a bit of detergent in the water and brush it on the seams with a clean paint brush so it wets the seams thoroughly for it all to take effect.

Carl R. I have a new van and have an identical situation. I have not done anything as the dealer told me that given time the stitching will swell and seal the leak. If I was going to do anything at all then a waxing seal would be the answer. Relax let it seal itself. The little leak should not caue any problems.
regards mick

Thanks to all for you input fixed the stitching but now find that the water is coming from the track it appears to be filling the track that the annex slides into and dripping inside any help would be great as we just keep getting down pour after downpour

I had a similar problem at Christmas after I got a zipper replaced in the awning of my camper. I went to a camping/canvas store and they sold me a product called "seam sealer" for $10 in a 50ml tube. I haven't tested in the rain yet though and not keen to use the hose on canvas witout being sure I can get it dry again at the moment.