lineTo ... > whats wrong with me!

hiya … i got an mc on stage … >

i just want a line to be drawn from the centre stage to my MC object which is being dragged around …

//inside a mouseDown function
mc.graphics.lineStyle(1,0xFFF);
mc.graphics.moveTo(this.x,this.y);
mc.graphics.lineTo(stage.stageWidth/2,stage.stageHeight/2);
e.updateAfterEvent()

hmm gotta be real simple - but ive gone mad and cant do it …