Seat reservation problem; Valence Tgv Rhone-Alpes Sud to Barcelona-Sants - ''won't arrive in time''

Hi, i’m from Italy
My friends and I have bought a global pass ticket for Spain, because we wanted to leave from our country, but we have a problem with the seats reservations, especially the one on the travel from Valence Tgv Rhone-Alpes Sud to Barcelona-Sants, because, when we are about to book the seats, they ask us the paper ticket but they won’t let us go on booking the seats saying that they wouldn’t arrive in time even though the on the site it says that we can book the seats at least 6 days before and we have plenty of time. Is there a way we can solve this problem? Can we book the seats in an other way?
thanks