It’s possible that the fare you purchased does not allow seat reservations at the moment. Only some of our fares allow seat selection free of charge when buying through our website.
Furthermore, passengers traveling with one of the following special services cannot reserve seats: on-board luggage, an extra seat, deported or inadmissible passengers, medical cases, on-board pets, medical devices, stretchers, unaccompanied minors.
Finally, if your flight is operated by another company, it is possible that the fare purchased may not allow you to reserve seats. (review the conditions of the transportation company)