If they were shipped it can really reduce their viability. I've had really bad hatches from shipped eggs as well, but sometimes that's the only way to get the breed & quality you want. Have you candled to see if there's any movement at all? I would think they were not alive after this long. I have been known to take a very sharp eyebrow tweezer and chip away at the top of the big end of the egg and look down into it to see if I can see any movement below the membrane. If you touch it gently with the dull handle-end of the tweezers and nothing respones - then the chick is dead. If you candle and still see fluid after this long, I would say they died sometime during incubation. Often times when I see fluid at this many days I don't open the egg as the can be rotten and explode on you - not a pleasant experience at all.
Good luck with your attempts to discover what's happening and better luck next time with the hatch.