There are tons of reasons the scales may not be moving. Depending on your workout routine, you may be losing fat, but gaining muscle, which can cause the scale to be pretty useless for tracking.
Are you taking measurements as well? If you haven't been, you should start! I went nearly 2 weeks without a single oz lost, but still lost a half inch off each arm, an inch from my hips and another half inch from my waist. Even when the scale doesn't move, I can see my progress and that helps keep me motivated. =)
Also if you're eating much salty food, it can cause your body to hold onto more water, in a day or so that will even back out to your 'normal' weight.