I'd like to be able to cause notification to appear on a Pi Desktop.
I've been running a recent Raspbian Jessie on a Pi 3, fully updated. I have libnotify-bin and notification-daemon installed (and rebooted thereafter). I am logged in as pi, and ps shows notification-daemon running.
However
$ notify-send Testing
has no visible effect. A quick search hasn't turned up a relevant logfile to examine, and Googling turns up stale info. What am I missing? What are my next steps?
Update: Steve's suggestion below solved the problem. While poking at it, I also was reminded that setting DISPLAY=:0 is necessary to cause notifications to appear from an ssh session.