Where is the line between being too hard or too easy on my daughter?

She is four. She said she wanted to take dance classes, so I signed her up for a preschool ballet/tap combo class. It was five weeks this summer and she did ok, but would randomly not participate. Overall, it was worth it, though.

Today was the first day of the “year” until the recital in the spring. She sat or laid by the wall for about 85% of the class. I am so disappointed that she didn’t even try. I feel like if I don’t say anything it is teaching her that it is acceptable to not try or give her best. On the other hand, I don’t want to overdo it for her age and make her feel bad about herself.