As has been mentioned in numerous places already... in SW:ToR, keys with modifiers, require the HOLD option to be enabled for them to work correctly.

http://www.dual-boxing.com/threads/4...l=1#post349807
http://www.dual-boxing.com/threads/4...l=1#post349810
http://www.dual-boxing.com/threads/4...l=1#post352950

http://www.dual-boxing.com/threads/4...l=1#post350055
- Need to enable the hold option for mapped keys for the modifiers to work
http://www.dual-boxing.com/threads/46370-GUIDE-Click-Healing-System-Using-Party-Frames
- Make sure to choose ON in the dropdown list for "Hold any Keystroke Actions while Hotkey is held" for this key, if you are using a modifier (Shift, Ctrl or Alt) for your ability ingame.