Anyway I eventually e-mailed Isabella and got his reply :-
Thank you for your enquiry. From the image you have sent, it would appear that your Fix On bracket needs to be repositioned. To achieve the optimal fit, it needs to be aligned with the seam on the side of the awning so that the bracket is situated half outside the awning canvas. Once this has been done and the roof rafter fully tensioned, this should alleviate the problem.
So if anyone is having the same problem that is the solution.