Box 2d SetLinearVelocity in 0 gravity

programming flash
1

I am using Box2d 2.02, and am having trouble with setting linear velocity of a body in 0 gravity. When I trace GetLinearVelocity() when left is pressed, it reports the correct vector (-20.0, 0.0) but the body does not move. It is a dynamic body. Is there anything I’m missing?

if (Key.isDown(Keyboard.LEFT)) {
                
                if (mover.IsSleeping()){
                    mover.WakeUp();
                }
                mover.SetLinearVelocity(new b2Vec2( -20.0, 0.0));

            }