Are you using the default number keys at the top of keyboard to switch screensets?
If you're using screensets with a great value than 9 (e.g. 11, 31, 99, etc) then hold down the Control key and press the numbers... e.g. Control, then hit 9 and then 9 again to access screenset 99.
Have you tried trashing your Logic Pref's file? (you might want to export your key commands from the Key Command > Options window menu first)
1. Quit Logic & Go to [Home folder]/Library/Preferences/
2. Move the file "com.apple.logic.pro.plist" to your Desktop.
3. Launch Logic.
(Logic will create a new preferences file automatically).
Hope this helps