Stretching/translating a layer into another document

Question

I probably just have my math wrong, but given a selection box boundary (or boundaries), I'm trying to resize it so that it's the size of a target document and then translate it so it's in the top-left corner taking up the whole screen (so what's in square selection takes up whole screen.  Now if I duplicate the layer in the same document and scale it using the document's dimensions and translate, it fills the whole screen.  However, if duplicate the layers into a target document and scale and translate according to its dimensions, the layer is the correct size, but wildly off position (most of the time off the page).  I would think the translation would be independent of the destination doc and based just on the scale and (minX,minY) of the selection box. 
Is my math off or is there something funny about duplicating a layer into another document?  I'm guessing it's the former, but I keep doing it in my head and the math looks sensible. 
var layer = app.activeDocument.activeLayer;
//layer.isBackgroundLayer = false;
var layers = new Array(thumbnails.length);
//layers[0] = layer;
for (var i = 0; i < layers.length; i++) {
    layers[i] = layer.duplicate(documentTarget);
var srcDocument = app.activeDocument;
app.activeDocument = documentTarget;
// for every layer, go through translating and resizing based on the box size
for (var i = 0; i < layers.length; i++) {
    var selectionBox = thumbnails[i];
    var scaleX = documentTarget.width.as("px") / (selectionBox["maxX"] - selectionBox["minX"]);
    var scaleY = documentTarget.height.as("px") / (selectionBox["maxY"] - selectionBox["minY"]);
    layers[i].resize(scaleX * 100, scaleY * 100, AnchorPosition.TOPLEFT);
    layers[i].translate(new UnitValue(-selectionBox["minX"] * scaleX, "px"),
                                new UnitValue(-selectionBox["minY"] * scaleY, "px"));

Answer 1

.. Why would minX,minY be different assuming the layer is duplicated to the topleft of the target document at 0,0?  
That was the point I was trying to make. That assumption is incorrect. The duplicated layer will not be at 0,0 unless both documents are the same size and resolution. The duped layer is centered in the new doc. Only when the sizes match will the positions match. Otherwise the new top left position could be anywhere including off canvas( negative values ).
If you don't want to change minX, minY for some reason you could add code to align the layer to the top left before the translate line.
function align(type){
   var desc = new ActionDescriptor();
     var ref = new ActionReference();
       ref.putEnumerated( charIDToTypeID( "Lyr " ), charIDToTypeID( "Ordn" ), charIDToTypeID( "Lnkd" ));
   desc.putReference( charIDToTypeID( "null" ), ref);
   desc.putEnumerated( charIDToTypeID( "Usng" ),charIDToTypeID( "ADSt" ), charIDToTypeID( type ) );
   executeAction( charIDToTypeID( "Algn" ), desc, DialogModes.NO );;
function alignTopLeft(){
  align("AdTp");
  align("AdLf");
app.activeDocument.selection.selectAll();
alignTopLeft();
app.activeDocument.selection.deselect();