(AS3) MovieClip panning X&Y

hey, im trying to pan a movieclip around my stage, in both x and y, depending on mouse location. i based the code for this on the tutorial found here.

the movieclip im working with is 1100x900 and the stage is 800x600.

public function constrainedMove(target:MovieClip, speed:Number, dir:Number):void {

			var mousePercentX:Number = this.mouseX/800;
			var mSpeedX:Number;
			
			if (dir == 1) {
				mSpeedX = 1-mousePercentX;
			} else {
				mSpeedX = mousePercentX;
			}
			
			var mousePercentY:Number = this.mouseX/600;
			var mSpeedY:Number;
			
			if (dir == 1) {
				mSpeedY = 1-mousePercentY;
			} else {
				mSpeedY = mousePercentY;
			}
			myBack.updateMe(mSpeedX,mSpeedY);
		
		} 

i have this code in main class and is called on every frame.

public class MyBg extends MovieClip {
		public var destX:Number;
		public var destY:Number;
		public var inMotion:Boolean = false;
		
		public function MyBg(){
			
		}
		
		public function updateMe(mSpeedX:Number,mSpeedY:Number):void{
			 //trace("Updating!");
			var speed:Number = 1;
			//trace("this.width: "+this.width+" stage.width: " + stage.width);
			destX = Math.round(-((1100-800)*mSpeedX));
			destY = Math.round(-((900-600)*mSpeedY));
			
			if (this.x == destX) {
				//trace("this.x: "+this.x+" destX.x: "+destX);
			} else {
				//trace("something");
				this.x += Math.ceil((destX-this.x)*(speed/100));
				inMotion=true;
			}
			
			if (this.y == destY) {
				//trace("this.x: "+this.x+" destX.x: "+destX);
			} else {
				//trace("something");
				this.y += Math.ceil((destY-this.y)*(speed/100));
				inMotion=true;
			}
		}
	}

and this is myBack’s class.

what happens when i run this code is that i can only scroll my image horizontally, but i want them to scroll independently. any ideas on why its doing this?