I installed and configured bumblebee and the bumblebee indicator once before on Ubuntu 13.04. It worked fine. I had to reinstall and did the exact same thing as before. Now the indicator on the "task bar" will not show up. Even if I start the program from the terminal. No output is given either. Is there a dependency that I am missing? I just don't know.
Download the icons from github (location: /bumblebee-ui-master/icons) and put them in your ~/.icons folder (if you don't have one create it). Everything should work just fine now. Even the menu entries for Bumblebee Applications Settings and Bumblebee Indicator will start showing up normally at the dash.