Passing mc name as as a parameter

I’m trying to pass an mc instance as a paramter of a function. is this possible because I keep getting errors.

function moveCircle(sIncrement:Number, sMovie:String):Void {
	sMovie._x +=sIncrement;

sMovie is the instance i’m trying to reference

	moveCircle(10, "mc_Circle");

this is the button code

I’m trying to do this to cut down on redundant functions I’ve used in the past for simple as movements and controls. Is this possible?