Android: RingtoneManager not set the default ringtone

Question

I am trying to change the default ringtone by programmatically. From a search I am getting the code like

  RingtoneManager.setActualDefaultRingtoneUri(
                mContext,
                RingtoneManager.TYPE_RINGTONE,
                Uri.parse(uri));

But when I try to change the default ringtone it's not changing in my phone.

Where am wrong?