Remote scrums are hard work. The first clue that something was wrong was when our sole remote coder volunteered to stop attending the scrum because he didn't find it useful.
This is a danger sign. Further probing determined that it wasn't that the format was wrong; it was just that he couldn't hear anyone. We're using Skype video calls, with the laptop sitting on a chair in its place in the circle, using the Macbook's built-in mic and speakers. While the mic's okay for 1:1 conferencing, it's not sensitive enough for people standing a couple of metres away.