Let me start off by saying I have a toon with a name that is not common, it has 2 capital letters:

http://us.battle.net/wow/en/character/sargeras/SuperLich/simple

And for the longest time, I was able to use greenwall just fine up until the WoD patch. I have reinstalled greenwall and even went as far as reinstalling WoW. Greenwall works just fine on any other character, expect for SuperLich.

The weird part is that I can see the other guild sending messages in gchat, but they can't see what I type.