GA Hunter,
Many law enforcement agencies use labs for detection and tracking dogs because they typically have great noses so the issue probably isn't his nose. I know many believe that labs don't have great noses but I have found it to be just the opposite.
The question that I have is how much drive does your pup have? Is he birdy...or on this forum gamey?? Most issues that I see with labs are a result of a lack of what many would call prey drive. Unfortunately much of this has been bred out of some lines of many of our hunting breeds...labs especially!!!!
Assuming that your pup has a lot of prey drive it's pretty easy to teach them to trail stuff.....
If he likes birds wing clip a bird (ducks work the best) and turn it loose and let it walk off (while your dog is watching). A few minutes after it goes out of site (even if its just 20 or 30 yards into thick cover) let your dog loose and encourage him to find it by using his nose. Pick a command and use it every time so he gets acclimated to searching with his nose ever time he hears it. Keep increasing the distance of the tracks and once he starts to understand the "search command" quit letting him see the bird (or other game)walk off.
Once he is good at this you can start using other things for him to track like a hind leg of a deer etc.
One of the best labs I ever owned would track anything that left a blood trail....Deer, ducks, geese, pheasants, whatever even if it was an animal that she had never been exposed to.....Just take her to an area give her the command and she would track what every went through the area and left a scent.
Just use whatever animal(s) you want him to track to train him with and he'll learn. Again drive is key!!
Hope this helps!!
Brian