I have installed via Ubuntu repository Thunderbird 31.4.0. I then installed Lightning 3.3.3 via the Thunderbird add ons menu. Lightning installed, but it doesn't function. My online calendar does not show up and there is an exclamation point next to the calendar name, indicating it's not working. Any suggestions? I'm new to Linux (Ubuntu), so if the solution requires anything beyond typical install/uninstall, I'd appreciate a detailed explanation. THANKS