Default [Need help] how to fix Unknown Ringtone under Notification Sounds

I have trouble with custom notification sound for different alert tasks such as: sms, mails, calendar, task,....

See attached picture

in ROM Viper 1.6.3 under Notification sounds of Personal/ Sounds

it shows up as Unknown ringtone under:

I can go inside to select different tones, then Apply, But it won't saved. All are set to the default tone
only Default notifications I can changed
Is there any way to fix ?