NullPointerException

[ductranit]

I get this NPE exception when start falling notes

Fatal Exception: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.graphics.drawable.Drawable.getIntrinsicHeight()' on a null object reference
       at dyanamitechetan.vusikview.VusikView$Notes.init(SourceFile:200)
       at dyanamitechetan.vusikview.VusikView$Notes.calculateNextStep(SourceFile:205)
       at dyanamitechetan.vusikview.VusikView.calculateNotesNextAttr(SourceFile:135)
       at dyanamitechetan.vusikview.VusikView.access$1400(SourceFile:16)
       at dyanamitechetan.vusikview.VusikView$FallNotesThread.run(SourceFile:267)

I have no idea why mNotesIconDrawable is null.