Scale From Center After Drag

I have an image inside a movie clip that a user can scale from its center using the slider…works great. However the use can also drag the movie clip. After the movie clip is dragged to a new location it and then scaled using the slider it jumps back to the center of the stage and then scales. I have tried modifying the x y of the movie clip but then the scale is no longer from the movie clip’s center. Any ideas?

var clipNativeX = holder_mc.x;
var clipNativeY = holder_mc.y;

function scaleClip(val:int):void
var trueScl:Number = val/100; // val is the value from the slider
holder_mc.scaleX = holder_mc.scaleY = trueScl;
// I think the problem is here but not sure how to fix
holder_mc.x = clipNativeX-(holder_mc.width/2);
holder_mc.y = clipNativeY-(holder_mc.height/2);