Why does my trace script give an application error?

Hi All

I have written a simple script to to trace a raster image using Illustrator.

The image can be traced using >Object > Image trace in Illustrator without any problems.

However, when I run my script I get the following error:  Application error 12321(some long number) 'MARC'.

Does anyone have any advice on how I could solve this problem?

Thank you!

Also, my code is below.

var jpgFilePath = new File ("/Users/Ellipse8.jpg")

createRasterItem(jpgFilePath)

function createRasterItem(jpgFilePath) {

var rasterFile = File(jpgFilePath);

var myDoc = app.documents.add();

var myPlacedItem = myDoc.placedItems.add();

myPlacedItem.file = rasterFile;

myPlacedItem.position = Array( 0, myDoc.height );

myPlacedItem.embed();

var thisImage = myPlacedItem.trace();

thisImage.tracing.tracingOptions.ignoreWhite = true;

thisImage.tracing.expandTracing();

redraw();

}