Hi Jim,
The red circle/slash means that ThinkEssentials could not communicate with the device. This either means that there isn't a good path to get to the device (either directly or hopping through other devices) or you have a bad antenna in your device or USB stick. How far is your PC from the device? Any Z-Wave device?
Also, is your USB stick plugged directly into your computer, or is it on an extension cable away from metal objects?
Chris