Originally Posted by gljurczyk
Here is a picture when the slide slip down on the left side fully extended. This stretched the fabric, There are screws on top, you can see how it is pulling down. You can install pop rivets as stated, but the cause is on top at the trailer not under the 4 wraps on the roller. The roller will walk being not level when brought in. This will also cause the set screw to make the whole bigger and it will walk and cause the wrinkle.
Regardless, the awning material should be centered on the roller, first,then the slide retracted and the material aligned accordingly in the track on the trailer and anchored. The material will eventually shrink or expand accordingly.