Hitting A Brick Wall

The boy has been on a tight leash lately. He has had no video games, friends or after school activities for 2 weeks and he is not allowed to stay home alone. His grades have gone up in most cases. But he still has been having troubles in one class. He worked on a project last week that we offered feedback and helped him improve and then Failed it. We had downloaded the instructions and made him practice his presentation and offered suggestions. I saw the grade and the boy was upset and said this that and the other thing. I emailed the teacher and asked what had happened. I got the response today that he never handed it in and that the teacher is getting frustrated with Nate because he has had to backtrack to find that missing assignments that I have questioned (based on the boy's work) are truly missing. We are having a meeting with him when he is available. I also received a phone call from his Math teacher this weekend. He was taking 4 steps forward and then failed to turn in an assignment. The teacher wanted to let me know ASAP so that this slip did not turn into a fall.

The boy has tons of support at home and at school, what the hell is wrong with him? I am at wits end!!!