I can't create a bootable OSX Mavericks Install USB Drive

I've downloaded Mavericks from the App Store, repartitioned a 32GB USB key, and followed the instructions. Specifically, I ran:

sudo /Applications/Install\ OS\ X\ Mavericks.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ Mavericks.app

Here's the output. As you can see, it fails with an error:

Ready to start.
To continue we need to erase the disk at /Volumes/Untitled.
If you wish to continue type (Y) then press return: Y
Erasing Disk: 0%... 10%... 20%...100%...
Copying installer files to disk...
Copy complete.
Making disk bootable...
Couldn't mount dmg /Volumes/Install OS X Mavericks/Install OS X Mavericks.app/Contents/SharedSupport/InstallESD.dmg (error code 112)Mount of outer dmg failed.
Done.

Help?

It turns out that the Installer Image did not download correctly. To address this I deleted "Install OSX Mavericks" from the Applications folder and then re-downloaded it from the App Store.

I had the same problem with a 16Gb USB. I tried it twice. First time I got error 112, and then an error 110 when I tried again.

I was about to download it again, but I tried a different USB 16Gb, and it worked with the same app file. So my tip, before you go downloading it again, try another USB brand.