Messaging Error ("We can't send a message at the moment")

Hey guys, I have Windows 8, and I get this error when I try to send a message:
"We can't send a message at the moment."

Screenshot of it: http://thetechrishab.com/scap/0013930.png

Please help me. When I try to click the "New Message" button (screenshot: http://thetechrishab.com/scap/0014331.png) I see no friends, this is the screenshot: (http://thetechrishab.com/scap/0012533.png)

I know that I have connected all my friends from Facebook. But why does this happen? Why can't I send message, or see friends who are online?

Please help me.

-TheTechRishab
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Are you behind a firewall that might be blocking messages? Such as a work or school computer?