Is it laziness?
There are plenty of reasons why homework is frustrating to someone that age. Hand cramps and sore backs, a feeling of being stuck in a tedious and pointlessly repetitive life. Hormones play an affect and your kid is probably under-exercised.
I don't know what will work. I just know that getting mad won't. If you can find out the reasons why he won't do it, you can find ways to compromise. And if it turns out to be laziness, you know where to start.