What has helped me with this exact situation is to call the parents and ask then what is going on.
I have found that sometimes (not all times) that this is the student just making it up cause they know (now they really know) that you wont call parents to verify this info.
Most of the times they are understandable. Sometimes they are not. If they are not understandable, just be kind and cordial and state the expectations of your class and follow whatever attendance/grading policy you have in place. If they don't show, at least you can rest knowing you have done everything you can and next year you can put this person as an alternate or remove from program due to many missed rehearsals, so it doesn't matter if they show up or not anymore.