Q: Text tone isn't working

Greetings selinafrommontreal,

Thanks for using the Apple Support Communities!

From your post, I understand that you purchased a tone from the iTunes Store, but it is not working as expected. 

Are you not able to assign the tone as described in the following article? 

Set sound options. Go to Settings > Sounds for options such as ringtones and alert tones, vibration settings and patterns, and ringer and alert volumes.

Sounds and silence - iPhone

If you are having a different issue with the tone, you can report the problem directly to iTunes Support by using the information in the next article. 

Report a problem with an item purchased from the iTunes Store, App Store, Mac App Store, or iBooks Store - Apple Support

Have a great day!