|Apple's System Preferences application has a cache file that stores all the installed preference panes (the new name for control panels) for quick access. Problem is, the System Preferences doesn't check to see if new preference panes have been installed.
There are two possible ways to fix this:
1) Delete the file called ".ApplePrefPanesCache" in your user folder. Note the period (dot) at the beginning of the file name. This indicates the file is invisible in the Finder. The easiest way to delete it is to open the terminal (/Applications/Utilities/Terminal) and type the following on one line:
Then press the enter key. The System Preferences must not be open when you run this command. Launch the System Preferences application to see if it has worked.
2) Copy (Don't move) the recently installed Haxie from /Users/yourname/Library/PreferencePanes/ (a quick way to get to /Users/yourname/ is to press the Home button on the Finder toolbar) into /Library/PreferencePanes/ if the last folder does not exist, it is safe to create it yourself.
Some currently released versions of our Haxies have a new installer that automatically deletes the .ApplePrefPanesCache file (it's safe to delete it) and should not experience the problem. We will roll the new installer into future releases of our other Haxies.