I would advise you to go into your Device manager on the machine where you ran your 'devbra', and see if thre is a entry for Media Changers. If there is, see if it can be expanded, and see if it contains things like the bus address
I suspect somewhere along teh way, you are goingto find something missing. Since it is missing at the OS-level, this is not a DP issue
Check your cabling, make sure that a connection has not worked loose, and that everything is terminated correctly