Trouble summoning friend with password

I was trying to get my friend to join my game but no matter what he could not see my sign. He is 10 levels below me and we both were at +2 weapons. The crazy thing is that he could put down his sign and I could summon him immediately. We both tried logging in and out to try and fix it.

Is this a bug or what? I had just helped him beat a boss and after that, no more sign. Is there a server issue causing this?