From Phyllis Fleming, (firstname.lastname@example.org)
If a dog is having trouble with this exercise, start by breaking down into parts that he can be successful with. Start back at about half the eventual distance. When the dog drops, walk in, praising quietly and feed the dog his favorite treat. THEN after praising him again for a good drop (while the dog is down) break the exercise and give lots of praise. Forget about throwing ANYTHING at a soft dog. Even food being thrown can upset them and if you miss the immediate area in front of his mouth you are *telling* him to get up or correcting him for doing so! Make sure your praise tells him what you are pleased with, such as "gooood drop".
After the dog is dropping reliably and confidently then start backing up until he can do the whole routine from full distance. When you have this go back to half way and throw in the sit (don't forget to praise the drop) and feed and praise as before. Once you have the drop the sit part will come quickly and you can add the recall. When you have the recall added in, jackpot when he is in front of you. Obviously, the next step is to start phasing out the food.