RE: shorthair troubles
First of all like mentioned above, your GSP is young and most likely has not had enough experience. Second, what I've always done (especially with young dogs) is to try and mark a few singles (easier to do with more than one person hunting) so you know the general area to take your dog to in order to find them. But before I go tromping over to the marked spot where I think the single is, I give the bird(s) some time to settle down and produce some scent. If you rush over to the singles immediately there won't be much scent for your dog to find. Lastly, I don't like to brag but I have two very good dogs (especially the older one when he was in his younger years) and I have spotted singles and cast the dogs towards them and absolutely could not find them. It just happens sometimes. Best advice is to work your dog as much as possible and keep it under control (i.e. don't let it run wild once the covey flushes). Good luck to you!
EDIT: sorry, I think I kind of summed up the previous post...it's late and I didn't feel like reading through the other 2 whole posts.