G.B.
Most dance school or gymnastics places have classes on the week nights. They do often have their recitals and make up days on the weekends but most teachers know there are situations like this. If you even go to court again you might add something about if the kiddo has an activity that ends up falling on his weekend he needs to make sure she is able to get to her activity.
As it stands now she'll never get to play soccer, softball, any sport actually. Most of them practice during the week and play on the weekends.
So he needs to come around on this or you guys compromise on his visitations. Either he needs to do a longer visit on school holidays to make up for missing weekends that she has activities or he needs to make sure she is able to attend. He is part of her life too and she needs him to be there for support too.