Nancy Kerns: Hi! I am Nancy Kerns, Editor of the Whole Dog Journal. The quality of your physical skills is important to effective training. Good timing is particularly important, particularly when a dog is moving fast or doing one behavior after another. If you click too soon or too late or inconsistently it's confusing to the dog. He might think that the behavior you want is sitting and then getting up, for example instead of just sitting.
You also need to deliver the treat quickly after you've used the marker. If the gap in time is too long, especially when your dog is in a kindergarten level of training he won't understand why he's being rewarded. If you use a reward that is too low value, it's inconsequential for the dog.
Dogs are masters of comparing the value of different options. If they have a choice between a low value treat and a chance to go play with another dog, they'll probably select the play session. It's not disobedience. It's just simple dog math. Don't be stingy with your treats. Again, with a little dog math, he may conclude it's more rewarding to go do something else.
When building a new behavior use a very generous schedule of reinforcement to keep your dog's interest in the training game. Also, be unpredictable with the type and amount of treats you give like a slot machine. When the dog does something really good keep his head in the game with a big jackpot. It's much more rewarding for the dog if you feed the jackpot with one treat fed right after the other than it is to give him a whole handful at once.
The location of your treat delivery is also important. Deliver them right on your dog's lips or you risk pulling him out of position. If you're teaching a sit for example and you feed the treat way up here, you risk teaching him that sit is just a momentary behavior. Sit for a second and you've wasted an opportunity to start teaching a nice stay to go along with that sit.
If something is not working, review some of these concepts and see if something you're doing might be accidentally undermining your efforts. If you're doing everything right, your dog should make rapid progress.