Is there somewhere for them to hide? Also some pods can be very small and hard to see. If there is no where for them to hide they make have went into the return pump and went to the display tank. I'm not really sure though. I bought pods a while back and they were all over the place for a while then disappeared into the Rock and sand. Try looking at your tank at night, especially with a red light.
If you got them from Aquarium Depot, which used to be Reefs2go, the pods are probably dead.
I hate to say it but as old as those pods were, you were lucky to have 5-10% alive if any and that is if they were refrigerated. I'd have a talk with that LFS owner. :hammer:
You would be far better off just getting some macro, scoop of sand, or even a few small rocks from a fellow reefer. Most reefers end up tossing macro and would be more then willing to give it away. A little from a few different reefers will give you a nice variety that is known to survive and thrive in our systems
That all said what's your location?