ADD/Gifted and we can't motivate him!!!

I am at my wits end! My gifted son is also ADD (taking Adderall xr). He is at a gifted and talented school. He just started 7th grade and is having a hard time. He is failing classes and is just not motivated. He doesn't put in the effort, he is disorganized, unfocused, always late, and generally doesn't really care to try harder. He is in denial (thinks he's doing okay). I am at a loss as to what to do next! His teachers are wonderful. They are all very good teachers and want to help my son succeed. My son just doesn't think most of this stuff is important and acts accordingly. He does careless things like leaving off the heading of his paper, not remembering (or caring) to show the teacher his notebook for the “EASY” 10 points every Friday. He doesn't complete his work and if he doesn't complete the work he doesn't turn it in at all because he doesn't feel it's worth turning in!!! I can't hold his hand and force him to care. Do any of you have any words of wisdom, advice or stories to share with me. I really think I need to find a special way to motivate him and make him care about his work. The teachers do not seem to think this school is too hard for him. They think that if he were to put forth more effort he would do fine. He doesn't think he needs to study for a test, yet is surprised when he gets an "F" on the test. When he studies he does well. I don't always know what’s going on because he is unorganized and doesn't tell me everything that is going on and due at school. The teachers and I have devised a plan to keep the information flowing better from school to home, but it is still a battle to get him to do the work. HELP! Any thoughts!!! Thanks for listening. It felt good to write this down. I am so glad I found this board!