In a small bowl, combine the wafer crumbs, pecans and butter; set aside 1/4 cup for topping. Press remaining crumb mixture into an ungreased 11x7-in. dish. Refrigerate for 30 minutes., Meanwhile, in a small bowl, beat cream until stiff peaks form; set aside. In a large bowl, dissolve gelatin in boiling water. Add pudding mix; beat on low speed for 2 minutes. Add sherbet; beat on low for 1 minute or until soft-set. Fold in whipped cream., Spread over crust; sprinkle with reserved crumb mixture. Chill for 1 hour or until set. Refrigerate leftovers.