. Both replies are right, niether explains the procedure to fix it. In your top rail and on your roller you will find a screw at each end that holds the fabric in place to keep it in 'time' through the fabric and its hem sown rope into the rig channel or the tube.
I suspect that at one or the other, a screw has failed to hold the fabric, allowing the awning to move out of 'time' forward or back. Mfgrs use sdst screws to secure fabrics, yet if the builder misses penetration of the rope hem with that screw, then it could mitigate an out of time.
Look for unequal spacing to narrow it down.
