You don’t have the right to receive compensation in the event of overbooking if denied boarding occurs because of force majeure or other disruptions not related to airline actions. For example, strikes, political unrest, bad weather conditions, airport operation failures, airplane manufacturing errors, birds flying into the engine etc. Also, your compensation may be reduced if you received other facilities from airlines in form of compensation, such as discount and gift vouchers. In fact, your flight arrival must be more than 3 hours later than it was planned in order to receive compensation. You will find more information in Air Passenger Rights.