Messenger App says password is incorrect

I am attempting to install a Jabber account onto the messenger app (Facebook, specifically). After putting all the pertinent information in (username@chat.facebook.com), when it starts to connect it says that the password is incorrect.

I used the exact same password to add Facebook to my Calendar just an hour or two ago. This isn't the first time that my Mac (and iCloud) hasn't been able to recognise the correct password. Sometimes, I've had to type in a password several times before it finally goes through. But this is unrelenting. Is there something I might be able to do?

I have Mac OS X Yosemite version 10.10.5. I'm not sure if that matters (maybe they disable the work around for Facebook to Jabber in this OS?)

Can anyone help me out?