Here is what I did.........
I have a ringtone app which I downloaded from the app store and then downloaded a couple of ringtones to my phone. I then hooked my phone up to iTunes (and what follows was the instructions from the ringtone app). Once my phone was hooked up to iTunes I looked under my phone and in where my apps are listed was the ringtone app and when I clicked on it my ringtones showed up in a list. Now I had to copy the ringtones to my desktop then copy them to my iTunes library (they default to the tones), click on tones in the Library to make sure they are there then copy them from there and place them on my phone in the tones folder. Once that was done I unhooked from iTunes and went to into settings and sounds and applied the ringtones that I just downloaded.
Not sure why there are soooo many steps, its kind of stupid and it could be just the app that i have downloaded but that is how I got it to work. The ringtone had to go through all those steps for my phone to "see" it. It actually took me longer to type out the instructions then it did for me to do it.
Hope this helps you.