Android Bitmap Scale error

i have a bitmap(bk) and i need to scale it to my device screen.

i try to do like this:

bk1 = Bitmap.createScaledBitmap(bk, (int)(bk.getHeight()/height1*bk.getWidth()), height1, true);

height1=device height and bk is the bitmap that i need to scale; when i try to debug i get the message

Source not found.

but the bk Bitmap isn't empty... My application force close when i run it. any1 can help me with this? i don't know what is the 4th parameter of the function but i get the error in any cases...