Ok, now play your instrument

My son is a fourth grader and is supposed to practice his trumpet every weeknight but in order to get him to play his dad and I must pull our teeth out to get him to pull the instrument out of the case and play the damn thing. Oh and the constant crying during the practice is never fun, either. His dad recently told him that he is to pick up his grade to an 'A' before the end of the semester in order for us to even talk to him about an electric guitar again. He was also told by his dad last night that he will lose a months worth of allowance if he does not pick it up to at least a 'B'.

I am at a loss of how else to motivate the poor boy to play his instrument. He is not an athletic type and thus we are trying to steer him in the ways of which he may become interested in something less physical but equally respected. In high school he will be able to get involved in computer graphics and/or graphic design but for now music is about it in the school he is in.