Why getDrawable() doesn't work on some Android devices?

I'm going to bet it is failing on getDrawable(R.drawable.rblack, getTheme()); which was added in API 21. Change that line to:

if(android.os.Build.VERSION.SDK_INT >= 21){
    rBlack = getResources().getDrawable(R.drawable.rblack, getTheme());
} else {
    rBlack = getResources().getDrawable(R.drawable.rblack);
}

ContextCompat.getDrawable(Context context, int id)