ActionScript 3.0 :: FileReference Error 1069 In Loaded SWF

I'm using FileReference to download an image directly from Flash. Works fine in my standalone SWF, but it throws the following error when it is loaded into another SWF:
ReferenceError: Error #1069: Property save not found on flash.net.FileReference and there is no default value.

Here's the code I'm using:
public function downloadImage():void {
var imageData:BitmapData = new BitmapData(photoFrame.width, photoFrame.height);
imageData.draw(stage, new Matrix(1, 0, 0, 1, -photoFrame.x, -photoFrame.y));
var jpgEncoder:JPGEncoder = new JPGEncoder(85);
var saveFile:FileReference = new FileReference();
saveFile.save(jpgEncoder.encode(imageData), "myImage.jpg");
}