I have posted the pictures for 5ptstar in regards to the above question.
https://www.flickr.com/photos/advance-design_parts_co/38253554191/in/album-72157631870734114/
https://www.flickr.com/photos/advance-design_parts_co/24382536148/in/album-72157631870734114/
https://www.flickr.com/photos/advance-design_parts_co/38253554441/in/album-72157631870734114/
It appears to me you have not pulled tight enough going in (probably a re-try in order). The lower retainer can be used for this purpose to hold it tight at the bottom while you pull it around. Once satisfied with the fit remove the retainer to secure both. Depending on temperature you can also carefully use a heat gun to help the corner fit. There hopefully will be others who chime in with suggestions.
https://www.flickr.com/photos/advance-design_parts_co/18149693683/in/album-72157631867396207/
This is the best picture I have of mine for reference.