I ran into the same problem a couple of times, had one family who showed up
in every census but one, but I did find them in tax records for the missing
year and the five years before and after. With another family I was looking
for, they moved to another county in the same state, then they moved back.
Guess they just wanted to make sure I was paying attention lol.
Good luck :)
Rena
http://freepages.genealogy.rootsweb.com/~wvmystica/