Custom ringtone displaying in Itunes as greyed out with circle beside it

Hello,

I have followed the protocols to create a custom ringtone however when I drag the tone into Itunes it is greyed out with a circle beside it (it cannot be played). The clip is 30 seconds and created from a purchased itunes track, I have been searching for the answer for hours but I can't seem to find a solution to this problem.

Thanks!