Blocking & unblocking system

It sucks.. that when i block someone which i didnt had as friend when i unblock them again it doesnt work. It shows this "Your message could not be delivered because you don't share a server with the recipient or you disabled direct messages on your shared server, recipient is only accepting direct messages from friends, or you were blocked by the recipient."

Please try to change it so if i block someone that isnt my friend then unblock him again i still can message them.