Sometimes when you reboot your hardware or just start it,
your z-wave USB key is not ready yet to accept your commands when PulseStation tries to connect to it.
This results in PulseStation z-wave service thinking it’s running, but it’s not actually connected to your z-wave usb key.
Inside the Z-wave service log files, you will see messages like:
2016-04-26 08:44:35.644 Warning, WARNING: Out of frame flow! (0x76).Sending NAK.
2016-04-26 08:44:35.644 Warning, WARNING: Out of frame flow! (0x00). Sending NAK.
In this case the solution is usually very simple: just restart the zwave service and everything should start working again.