Did you try to run alltray from terminal to see if any error message comes up ?
It seems to be working fine here.
BTW, I don't think this is the best way to minimize Thunderbird to the tray. There is an extension called MinimizeToTray in Thunderbird which does that very well. To install it, open Thunderbird, go to the menu->Tools->Add-ons and search for "minimizetotray".
Did you try to run alltray from terminal to see if any error message comes up ?
It seems to be working fine here.
BTW, I don't think this is the best way to minimize Thunderbird to the tray. There is an extension called MinimizeToTray in Thunderbird which does that very well. To install it, open Thunderbird, go to the menu->Tools- >Add-ons and search for "minimizetotray".