Printing Bitmap producing blank image

I'm trying to capture a view as a screenshot and print it via bluetooth using (Xprinter), but everytime i try to convert the bitmap to greyScale it produces an empty bitmap.

here is my captureScreenshot method, it seems like well..

  public static Bitmap captureScreenshot(View view)  {
    Bitmap bitmap = null;
    String fileName;
    try {// create bitmap screen capture
        view.setDrawingCacheEnabled(true);
        bitmap = Bitmap.createBitmap(view.getDrawingCache());
        view.setDrawingCacheEnabled(false);
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        Bitmap.CompressFormat compressionFormat;
        int filename = view.getId();
        if (filename == -1) {
            filename = 1010; //something
        }
        //Little bit of compression. JPG if too big, PNG if all good
        if (getBitMapSize(bitmap) > 750000) {
            compressionFormat = Bitmap.CompressFormat.JPEG;
            fileName = filename + ".jpg";
            Log.e("checkResized", "JPEG");
        } else {
            compressionFormat = Bitmap.CompressFormat.PNG;
            fileName = filename + ".png";
            Log.e("checkResized", "PNG");
        }
        bitmap.compress(compressionFormat, 40, outputStream);
    } catch (Exception e) {
        Log.e("checkE",e.toString());
        //All kinds of exceptions
    }

    return bitmap;
}

and here the converting to grayscale method, which i think the problem is here..

 public Bitmap convertGreyImg(Bitmap img) {
    int width = img.getWidth();
    int height = img.getHeight();
    Log.e("printError", width + " ss "+ height);
    int[] pixels = new int[width * height];
    img.getPixels(pixels, 0, width, 0, 0, width, height);
    //The arithmetic average of a grayscale image; a threshold
    double redSum=0,greenSum=0,blueSun=0;
    double total=width*height;
    Log.e("printError", total + " ss ");

    for(int i = 0; i < height; i++)
    {
        for(int j=0; j<width; j++) {
            int grey = pixels[width * i + j];
            int red = ((grey  & 0x00FF0000 ) >> 16);
            int green = ((grey & 0x0000FF00) >> 8);
            int blue = (grey & 0x000000FF);

            redSum+=red;
            greenSum+=green;
            blueSun+=blue;
        }
    }
    int m=(int) (redSum/total);
    //Conversion monochrome diagram
    for(int i = 0; i < height; i++)  {
        for(int j = 0; j < width; j++) {
            int grey = pixels[width * i + j];
            int alpha1 = 0xFF << 24;
            int red = ((grey  & 0x00FF0000 ) >> 16);
            int green = ((grey & 0x0000FF00) >> 8);
            int blue = (grey & 0x000000FF);
            if (red>=m) {
                red=green=blue=255;
            } else  {
                red=green=blue=0;
            }
            grey = alpha1 | (red << 16) | (green << 8) | blue;
            pixels[width*i+j]=grey;
        }
    }
    Bitmap mBitmap=Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
    mBitmap.setPixels(pixels, 0, width, 0, 0, width, height);

    invoicePic.setImageBitmap(mBitmap);
    return mBitmap;
}

and when i try to print a drawable image , it prints very well! please help me to find the error. thanks.