This. You need to make sure you select the keyboard icon in dropzone otherwise pressing "L" just toggles looping in Sonar's control bar.
Cheers,
Gary.
Current configuration:
Core i3 Laptop / 8GB RAM; Sonar Platinum (replaced with REAPER); Roland Quad Capture interface; Alesis Micron; Roland XP30; Akai Mini MPK; Akai S2000