Device unique ID using luna-send

[czechdev]

Hello there,
I'm trying to get the device unique identifier (described at developer.palm.com/index.php?option=com_content&view=article&id=1550) in the console (needed for a shell script) using the luna-send command. Currently without luck. I'm using the following command:

luna-send -n 1 palm://com.palm.preferences/systemProperties/Get {\"key\": \"com.palm.properties.nduid\"}
** Message: serviceResponse Handling: 2, {"returnValue": false, "errorText": "missing parameter key"}

Am I doing something wrong? Should I use another way to determine the unique ID? Please note that I don't actually have the device, this is the emulator output (and may be the problem).