Cleats are the small pieces that go across the ramp to keep their feet from sliding.
You need to add something that's about 12 inches tall under the end of the ramp to make much of a difference in the angle.
That is the BEST wing clipping illustration!!
A pic of your ramp would help.....it's probably either too steep or the cleats are too far apart...or both.
Cleats work best about 4" apart, angle of about 30 degrees from horizontal.