Any chance you've given it
too much water? Are the roots rotting? Have you considered getting/making some
compost tea and watering it with that to help?
Was the tree bare-root or potted? I've read that there's a specific microorganism that Maple trees require. If it was bare root, you might try finding someone with a healthy maple tree and get a bucket of dirt from them?
I agree the tree doesn't look terribly happy in the picture, but I usually don't plant maple trees - Mother Nature plants waaayyyy... more than we can use in some very troublesome spots like our eves troughs! I wish yours luck.