PNGEncoder Problem

programming flash
1

hey! im having a weird issue

when i use PNGEncoder from adobe
I get this error

here is my code


var bmd : BitmapData = new BitmapData( maskMC.width, maskMC.height, true, 0x00000000 );

bmd.draw( ContainerMC, new Matrix(), null, null, null, true );
			
var byteArray : ByteArray = new PNGEncoder.encode(bmd);

Im getting this error

1048: Method cannot be used as a constructor.

Any idea why?
Thanks