User Can't Be Enrolled

Hello,

I have a user who was enrolled in a course for testing purposes, and she completed the course, made comments, and I updated the course. I'm now trying to enroll her in the course to test the updated version, and every time I enroll her it says "User enrolled", but her name does not show up on a list of enrolled users, and she does not receive the enrollment notification. Can someone help let me know what I'm doing wrong?