[Ifeffit] problem with feeff.inp

Dear I have some problem with a very easy simulation. Everytime I try to introduce a potential with more elements, for instance POTENTIALS 0 26 Fe 1 26 Fe 2 29 Cu the program stops the simulation with a message that I do not understand and that is attached to this mail. This 'weird' behavior does not happen with a monoatomic potential like POTENTIALS 0 26 Fe 1 26 Fe and in this second case everything works perfectly. I would be very glad if you will have any suggestion. Thank you in advance Sebastiano Cammelli