Can't hold class on tattooing?

I created a sim that has level 10 tattooing skill, and built him a small tattooing business on his lot, to be my sim's tattooing mentor. Then I went back to my sim and visited the business and she went to the hobby board to ask him to start a class - it is giving me the option for him to start a class in a couple of other skills he has but not tattooing.

I have sent my sim back to her home lot and returned just to see if that changed the offerings but they're the exact same. I want to take a tattooing class by this sim. Thank you!