Sometimes when I use Disk Utility to mount a disk image that's on my Time Capsule (say "sam.dmg"), the folder of the mounted disk image (say "SamsMounted") appears empty. By opening Terminal.app (in the Utilities folder, which is in the Applications folder), I can see that SamsMounted is owned by another user (say "notsam"), rather than me ("sam"). That's why it's not showing me any files. In Terminal, I type:
ls -ld /Volumes/SamsMounted/
and it shows me:
drwx------ 123 notsam staff 45678 Jun 15 2012 /Volumes/SamsMounted/
You can see that SamsMounted is owned by "notsam", which I ("sam") can't read. This doesn't always happen. Sometimes it works properly and is owned by "sam", and I can see my files in the disk image. If it does happen, I seem to be able to fix it by ejecting SamsMounted, and then mounting it by typing into Terminal:
hdiutil attach /Volumes/Data/sam.dmg
instead of using Disk Utility.