I was zakking and died, for some reason the res wouldn't work. This has been reported before, hope this can be looked into.
How far away from you was the resurrecting person? And was the priest/bishop in your party at all times or did they join to resurrect you?
There is a bug in which the ress skill gets cancelled when you get hit while casting it. I'm not sure about the exact details, as I'm not a bish, but this is what I've heard.