Key UP and down handler problem help!

1

it has no error, it traces down when i pressed and up when I released, but it keeps on walking and attacking even if I released the button whats wrong with the code ?.

                    addEventListener(Event.ENTER_FRAME, enterFrameHandler);
        stage.addEventListener(KeyboardEvent.KEY_DOWN, keyDownHandler);
        stage.addEventListener(KeyboardEvent.KEY_UP, keyUpHandler);
        
    }
    
    private function enterFrameHandler(e:Event):void
    {
        // gravitate the player
        gravityy += 2;
        
        // move the player
        _hero.x += gravityx;
        _hero.y += gravityy;
        
        // process collisions
        processCollisions();
        
        // scroll the stage
        scrollStage();
        
        //movement
        
            if(leftKey)
            {
            gravityx = -mainSpeed;
            _hero.scaleX = 1;
            _hero.gotoAndStop("walking");
            
            }
            
             if(rightKey)
            {
            gravityx = mainSpeed;
            _hero.scaleX = -1;
            _hero.gotoAndStop("walking");
            }
             if(aKey)
            {
            _hero.gotoAndStop("slash");
            }
            
    }
    
    private function keyDownHandler(e:KeyboardEvent):void
    {
            if(e.keyCode == 37)
            {
            leftKey    = true;
            trace('down');
            }
            
            if(e.keyCode == 39)
            {
            rightKey = true;
            trace('down');
            }
            
            if(e.keyCode == 65)
            {
            aKey = true;
            trace('down');
            }
        
    }
    
    private function keyUpHandler(e:KeyboardEvent):void
    {
            if(e.keyCode == 37)
            {
            leftKey    = false;
            trace('up');
            }
            
            if(e.keyCode == 39)
            {
            rightKey = false;
            trace('up');
            }
            
            if(e.keyCode == 65)
            {
            aKey = false;
            trace('up');
            }
            
            
        
    }

it has no error, it traces down when i pressed and up when I released, but it keeps on walking whats wrong with the code ?.
thanks in advance , !