If that new, have Sears
come out and fix it. Maybe they sold you a lemon.
There is a list of things which can go wrong in the booklet, try going through that. Might be something simple.
As for what can cause the problem, well. A failed pump will prevent water draining. The machine won't spin above a certain water level in the tub.
Of course, a sock or something like that in the pump or hose will do it,too.
Or the drain hose has got a kink in it when raised to the sink level somewhere you wouldn't expect it. But since you say it drains ok when you lower the hose, I suspect a non-consumer failure and that is why you should call Sears right away. You might try to track the problem down a bit more: Will it spin on its own after you have drained it? Or no spin at all?
May just be a loose wiring harness...but then have the repair person check everything else in the machine. They don't unsnap themselves unless the machine got some very rough handling.