Device not found or cannonot be opened

Hell:

I have an old emx module which I upload a new tiny bootloader & sdk4.2, no problem (so the usb cable is working) However, when I hit F5 to download a simple program, I get:
DEVICE NOT FOUND OR CANNOT BE OPENED - -USB:EMX
An exception occurred while attempting to launch the debugger. Object reference not set to an instance of an object

…any thoughts on what this means or how to fix it? Any settings I might check would be appreciated