Bringing up boys: Homework

I hate homework.
I hate it because The Boy hates it.
I hate it because it is SUCH a trial and I always either a) land up shouting at him to get on with it or b) land up doing it myself after shouting at him if only to get the wretched stuff over and done with before midnight.
I'd like to say he is fine in the classroom but from my conversation with his form teacher this morning he isn't. He flops about not getting on with it in exactly the same way as he flops about not getting on with it at home.
How can I get him to wake up to the fact that the quicker he gets his homework done the more time he has for doing stuff he enjoys? How can I get him to focus?
I swear if I left him to finish his homework all by himself he would still be sitting at the dining room table the following day with not a word written down or a sum answered.
I want to shake him!
I've lectured, I've cried, I've timed him, I've bribed, I've threatrened, I've taken away treats but NOTHING gets through to him.
Is he stupid or something?
It gets to the stage that I just want to run screaming from the house as soon as I catch a glimpse of his Prep Diary. It's not funny you know. I thought once I had left school I would NEVER have to do homework again and now look whtat's happened!
You know they don't tell you this in any of the baby or toddler manuals.