Hello and welcome to BBB! I use Trillian also so I'll do my best to help out. When you install the widget, you should get a separate popup box that asks for a name and the date for the countdown. Were you able to see that box and enter the data in those fields?
Did the contact list go blank upon just trying to install the widget or when you clicked ok after entering the data? Also did you try closing Trillian and re-opening it?
I will tell you Trillian is heavily Flash driven. You should make sure you version of Flash is up to date.