Flash :: TargetMC And The Signature Child All Change Color?

I have this project where a user draws dynamically her signature with the mouse on an area and then, on another frame and after the signature is drawn, he can changes the color of the signature by clicking some buttons, each with a different color.I'm using this to capture the signature to another frame:

The Button that triggers the capture event:

//targetMC is an MC to where the signature will be copied

function buttonClick(event:MouseEvent):void{
capture(drawingBoard_mc, _targetMC);[code]........

My problem is the _targetMC and the signature child all change color, and i just want the child/signature..I'm using var myMC:DisplayObject = DisplayObject(_targetMC.getChildByName("signature") as DisplayObject); to access the signature child, but the container mc (_targetMC) also changes color... What i'm i doing wrong?