I would think that they way you fitted the paddles was slighly wrong. With a new paddle make sure that the inner tub with the missing paddle is at the bottom of the tub.
dry fit the paddle but do not press it home, check that the lugs are facing towards the rear of the inner tub, once you have made sure of this push the plastic paddle home, then push towards the rear machine and pull the paddle to the front of the machine to lock the paddle in place.
David SR
September 2009