I had this error come up again. Its related to the inability of NAS Alarm being able to find the devices to play on ie remote speaker. When it occurred I opened the alarm and the scheduled item in question and what I noticed was that I was unable to change the device, in fact no other available devices were shown. I opened audiostation and similarly there were no available devices. A quick fix for this is to restart audiostation through package centre. I still dont know why this occurs or how as there is nothing happening either on the NAS or in NAS Alarm that I can think of to cause it but it appears more likely to be an issue with Audiostation rather than NAS Alarm.