FREBitmapData.acquire() occure error..#3503

Hello..

I want to send image from flash to native extension..

so i call acquire() for FREBitmapData in native extension code..

but The Code is occuring the error below...

Error: Error #3503: The extension was left in an invalid state.

Why does this error occur?..

The source code is below..

[FLASH CODE]

protected function onMouseDownHandler(event:MouseEvent):void

{

          var bitmap:Bitmap = new IMAGE_FACE() as Bitmap;

          faceDetector.findFace(bitmap.bitmapData);

}

[NATIVE CODE in Extension]

public FREObject call(FREContext freContext, FREObject[] arguments)

{

          Log.i("air.extension", "[FaceDetector2.findFace()]");

          try

          {

                    FREBitmapData freBitmapData = (FREBitmapData) arguments[0];

                    freBitmapData.acquire();  <==  ERROR : Error: Error #3503: The extension was left in an invalid state.

                    Log.i("air.extension", faceInfo.toString());

                    int width = freBitmapData.getWidth();

                    int height = freBitmapData.getHeight();

                    ByteBuffer byteBuffer = freBitmapData.getBits();

  int[] buffer = byteBuffer.asIntBuffer().array();

  faceInfo.nbFace = FaceEngine.FindFace(buffer, width, height, faceInfo);

          }

          catch (IllegalStateException e)

          {

                    // TODO Auto-generated catch block

                    e.printStackTrace();

          }

          catch (FREInvalidObjectException e)

          {

                    // TODO Auto-generated catch block

                    e.printStackTrace();

          }

          catch (FREWrongThreadException e)

          {

                    // TODO Auto-generated catch block

                    e.printStackTrace();

          }

          finally

          {

            }

          return null;

}