That is a generic error that occurs when you haven't installed the correct files before flashing or your phone is not currently at STOCK level.
Here are links to the STOCK GB files:
Download Links
Direct Mirror download
If you are currently running Gingerbread you must RE-INSTALL the STOCK 6.15.219 OTA including wiping user data and cache. Then when it restarts you don't even need to let it boot, just hold down Volume Down + Power and wait for it to turn off. Power back up holding both volumes + power and run the leak install. So, just do two installs back to back. First flash the STOCK OTA then immediately flash the 213 leak.
If you can't find the 213 leak link here is a
Mirror copy
The error message means you have modified files on your phone so the OTA version check can't verify you have the correct version.
If you are running a leak and want to update to a newer leak I wrote a menu driven script to prepare your phone for the update. Follow instructions in this post:
http://www.droidforums.net/forum/droid-4-roms/212634-simplified-211-update-guide-10.html#post2158860
Tom