Unable to join windows 10 edition and pocket edition...

When trying to join windows 10 edition and pocket edition 0.12.1 build 9 it doesn't work! When trying to join a pocket world with windows 10 edition it says locating server and after some time it says disconnect before i even join. When trying to join a world hosted by windows 10 with pocket it says outdated client. I'm not sure if this is a bug or not so i'm sorry if it's not. I just heard they are supposed to be cross compatible.