I usually use this little treats to teach my dog when he's behaving properly or when learning some trick and they work really well, he loves them.
When I take him outside to play (I usually take him on weekends to throw a frisbee) I want to reward him for catching the disc on the air or if he obeys when I tell him to stay. But in these cases he completely looses interest on the treats and won't eat them. The only thing in his mind is the frisbee and nothing else (it was difficult to teach him to stay and not run right away every time the disc is flying).
He obviously gets overexcited about the disc (we only let him play with it outside), but why would that make him reject the treats? I have tried to use the throwing of the disc instead as a reward, but it is much simpler to use the treats.