Used Aircraft Paid For Problem O2

I paid for a Boeing 707-420 and I have not been able to use it for my routes. It says it is idle when I go to choose the aircraft and I choose the Boeing 707-420, and no aircraft shows up. It has 0 for aircraft with insufficient hours and 0 for  aircraft with incompatible schedules. It has a long enough range, since I am only trying to fly it from Naples-Capodichino to Kiev-Boryspil. The plane was recently taken back from Sun Air of Skandinavia for not paying, according to the aircraft history. I dont know if that has something to do with it or not. The aircraft ID is 8540. Thanks for any help you can give. My airline is Ukraine Air in World O2.