Script to move layer in photoshop

I'd like to have a script that moves one of two layer in a photoshop session by one pixel, save the output as a png and repeat. Here's my attempt (it complains that transform is not avaialable, but I'm using CS6):

// Save selected layer to variable:

app.preferences.rulerUnits = Units.PIXELS;

var docRef = activeDocument;
var layerRef = docRef.activeLayer;


for (var dy = 1; dy < 20 ; dy++) {

MoveLayerTo(layerRef,-1,0);

        var opts;
        opts = new ExportOptionsSaveForWeb();
        opts.format = SaveDocumentType.PNG;
        opts.PNG8 = false;
        opts.quality = 100;

        var suffix = zeroPad(dy,5)
    var pngFile = new File("/path/to/file/"+suffix+"filename.png");

    //Folder path for new images

    docRef.exportDocument (pngFile, ExportType.SAVEFORWEB, opts);

}



function zeroPad(n, s) {   
   n = n.toString();   
   while (n.length < s)  n = '0' + n;   
   return n;   
};  

//******************************************
// MOVE LAYER TO
// Author: Max Kielland
//

// Moves layer fLayer to the absolute
// position fX,fY. The unit of fX and fY are
// the same as the ruler setting. 

function MoveLayerTo(fLayer,fX,fY) {

  var Position = fLayer.bounds;
  Position[0] = fX - Position[0];
  Position[1] = fY - Position[1];


  fLayer.translate(-Position[0],-Position[1]);
}