Q: contact ringtone on iPhone 6

Hi MarkfromMesa,

I understand you are trying to assign a ringtone to a contact on your iPhone.  Is this a ringtone you purchased or created?  Does the ringtone work for any other contacts?  Is it possible that you have duplicate contacts in your address book?

Try deleting the contact and restarting your iPhone.  Then add, the contact and assign one of the regular tones to him/her.  Next, try adding your preferred ringtone again.  The resources below will explain more:

Ringtones and vibrations - iPhone User Guide

How to sync ringtones to your iPhone

Take care,