There is still surface film on the water's surface?
Most likely the Surface Skimmer is too low. Adjust the skimmer up, the goal is to create surface tension on the incoming water which will pull the surface film into the intake grates. You will need to find the right level on your aquarium to set the Surface Skimmer, every aquarium is unique.
The water level in my rear chamber drops as I raise the Surface Skimmer
Add new water to the rear chamber while the filtration pump is on. Because the amount of incoming water has changed an adjustment will need to be made to set the water levels to the new part.