Student is signed up and I am coach, but it said he hasn't joined class.

Hi Dana,

It may be that the student added you as a coach but didn't join your class with the class code. In this case, you will need to manually add the student to your class. There are instructions for doing this here: 

https://support.khanacademy.org/hc/en-us/articles/360030762612-How-do-I-add-existing-students-to-a-class-in-my-Teacher-Dashboard-

I hope this helps! Please let me know if you have any additional questions!