I probably can't help, but things to check:
(Double-)check the key-binding;
Does it work with just selected text, rather than the whole file;
Use puts/print for the output;
The output could be in the Console (ctrl-' (apostrophe) in Windows), or (according to the 2nd plug-in) display in the status bar;
It could be a path issue:
"If your Coffee binary isn't in /usr/local/bin then you can edit binDir in CoffeeScript.sublime-settings"
But I'm just offering a second voice to your endeavour