Cleaner Shrimp Won't Clean!

[nanmer]

I have two cleaner shrimp that are lazy! They are good enough size that they should not be afraid and most of my fish are an inch or two (do have a hippo tang that is about 4 inches). Is this a learned behavior? I read about other shrimp setting up cleaning stations ... mine, not so much! They will clean my hand if it goes in their cave and at night they sleep in a different location (not totally sure where)

Would more shrimp be better? With a hippo tang I would really like a working crew to keep him clear of ich.