Message Indicator for Empathy in Ubuntu 12.04 not working?

After I upgraded my Ubuntu to 12.04 LTS, the message indicator (or, Messaging Menu) doesn't notify me for incoming messages anymore. The little envelope in the notification area used to turn green when I got a new message from Empathy. But it does not do it anymore, and other nice integration between Empathy and the applet was gone. There was still Notify OSD, though. But it will only display the bubble for 5 seconds. So if I was AFK and someone sent me a message, I was not notified in any obvious way.

This has bothered me for a little while, and finally I found the solution. I have to install a plugin for Empathy, which is called telepathy-indicator. It can simply be installed by the following command:

sudo apt-get install telepathy-indicator

Or, if you are not familiar with linux shell, go into Ubuntu Software Center and search for Empathy, and telepathy-indicator is listed as an Add-on there.

Then what you need to do is just restart your computer (or, log out then log in), and you will be notified whenever a message comes in.