Explanation
The Mac OS 8.6 updater checks whether an item is already installed before attempting to update it. If the item is not already there, then it assumes the user does not need or use the item, and the updated version is not installed. Also, the installer sometimes checks in specific locations for an item. If the item has been moved, the updated version will not be installed.
Example
Shameka Green opens the Desktop Printer Utility but gets an error stating that the application does not work with the current version of PrintingLib installed. This is because Shameka moved the previous version of the utility from the Apple LaserWriter Software folder of the Apple Extras folder before running the Mac OS 8.6 updater. So, the newer version of Desktop Printer Utility, which matches the updated PrintingLib, has not been installed. (Note that not all configurations yield this error, this is just an example.)
Resolution
Reinstall the component from the Mac OS 8.5 Installer, using the Custom Install feature. Then, run the Mac OS 8.6 updater again.