Ukelele keyboard not found by System Preferences I'm trying to install a custom keyboard layout I made in Ukelele that makes extensive use of dead keys and Unicode special characters. Ukelele seems to work fine and installation works for test keyboard layouts that contain fancy unicode characters. (By installation I mean copying the file into /Library/Keyboard Layout/, restarting, and checking System Preferences.) But the keyboard I actually want is never appears in System Preferences. I've tried overwriting a test keyboard that was found with the .keylayout file, resulting in the found keyboard vanishing from the list of keyboards in System Preferences. I've tried opening the console log and looking for XML errors and I don't see any; similarly I've run the file through a web service to check the XML which didn't turn up any problems. My best guess is that there's some problem with the XML produced by heavy editing, but I'm not finding it. How do I fix this? 

I'm running OS X Yosemite 10.10.5 and Ukelele 3.0.3.70. 
Link to the problem file.
In my opinion, you need a «your_language.bundle» in the /Library/Keyboard Layout/, which contains your "PhysicsType1 (MathPhysics)"

Then
Try pressing the "+" in the System Preferences> Keyboard> Input Sources, and then select the language in the list that appears, select your "PhysicsType1 (MathPhysics)"