Pheasantlab.......Did you use the a whistle while you were doing basic obeidence on the sit command? One toot of the whistle will replace the verbal sit command down the road.

While walking with the dog at heal....command sit...whistle...sit.....after a few sessions the dog will pick it up. Eventually you will not have to use the verbal sit. As the dog progresses....start increasing your distances...before you know it he will be sitting on the whistle at 50 yards.

Good Luck and Good Training