Since the 1.02 patch a little while ago, maybe 11 or so hours ago. Summon Signs have been broken. The majority of people cannot summon or place their summon signs down. This is a problem with the Dark Souls II Servers and not your connection or anything. Invading is mostly broken as well.
Taken from Reddit -
"jsauce2 Namco Bandai ComMang 121 points 6 hours ago*
Our QA team had the following on this topic. I can't say this is the case for everyone, but this is a possible explanation:
If a player tries to make a connection (summoning, getting summoned, etc.) and it fails. Due to servers being overloaded, spotty internet at the time, whatever - Then the game servers put a soft ban on that player for a short amount of time 5, 10 minutes maybe. During that time, if you try to put down a sign, it'll get rejected. They speculated that while patching was going on that the servers were just exploding and therefore things were a little rough.
I'll continue to monitor this thread to see if that may or may not be the case and pass everything along. Feel free to add an update to your post if things have changed for you. I'm hoping this resolves itself now/soon. Thanks <3
Edit: The patch was to fix an issue some folks were having where they had corrupted or broken saves.
Edit2: Ok so it's definitely more widespread than a few people and probably not related to what I stated above - Thanks for the info - We're working to solve as soon as possible. If I hear anything else I'll add it here.
Edit3: FromSoftware has been just arriving in their offices over the last few hours and I expect things to smooth out or to hear some more information from them. Thanks for being a cool community and I'll keep updating if I have anything more."
Just thought I'd let everyone know!