Compressing bitmap data

I'm afraid that nothing I do can get the given example to work, using either the jpg encoder or the png encoder, whether in an <fx:Script entity, or in an external class. Always it gives one of the two following errors (based on where and how I instantiate the encoder options object)

ReferenceError: Error #1065: Variable flash.display::PNGEncoderOptions is not defined.

and

VerifyError: Error #1014: Class flash.display::PNGEncoderOptions could not be found.

/* more verbosely */

ReferenceError: Error #1065: Variable flash.display::PNGEncoderOptions is not defined.

at classes::PngEncoder()

at components::ChoosePictureButton/choosePictureLightboxClosed()

Here's the class I'm currently using, though it represents only one iterative attempt of dozens and dozens.

package classes

{

import flash.display.BitmapData;

import flash.display.PNGEncoderOptions;

import flash.geom.Rectangle;

import flash.utils.ByteArray;

public class PngEncoder

{

public function PngEncoder(bmpData:BitmapData, png:ByteArray, fast:Boolean)

{

bmpData.encode(new Rectangle(0, 0, bmpData.width, bmpData.height), new flash.display.PNGEncoderOptions(fast), png);

}

}

}