If you're having trouble getting a sparsebundle disk image to cooperate with hdiutil, disk utility or just mounting via the finder, it's probably got an incomplete "band" due to a crash or inconvenient network disconnection (in the case of sparsebundles mounted from a network volume).

To fix it, delete (or more safely, move) the last "band" in the bundle (see thing.sparsebundle/bands). It should be the last one, sorted alphabetically by name, and probably the smallest.

I have a sparsebundle with World of Warcraft in it, stored on an Opensolaris (yay, zfs) machine and accessed via NFS. I took the laptop to work one day and forgot to unmount the sparsebundle. When I got back home, it wouldn't remount, saying "resource temporarily unavailable." Grr. Removing the last band fixed it.