Either no primer hole or the primer was seated sideways. It may have been seated just right so the firing pin ignited the primer compound, but the off side of the primer cup prevented any flame from reaching the main charge. Probably a good thing, too.
I have seen several occurances of primers not properly seated on factory loads, but not very many cases without flash holes. Most fail to even ignite the primer compound as it is reduced to a powder during the seating process and falls out.
Pull the bullet, dump the powder and look inside with a light to see if there is a flash hole. That way, you will know one way or the other. Please don't pull a "Gomer" and try to pry the primer out!
If you just have to do that, make sure you saturate the primer with WD-40 or a petroleum based penetrant and WAIT!