Discovering and importing Tivoli Provisioning Manager data

Anyone can help me understanding this message, when I select one (or some) of the Lab Resources in the "All Lab Resourses" view?
I'm using a RQM-TPM Adapter to discovery my phisical machine, and what I see in the "All Lab Resources" view is in effect what I would expect (the list of the machine in my test lab).
But stil do not understand why this message happen:

"One of the machines selected is not discoverable. Discovery disabled. For more information see the help topic: Discovering and importing Tivoli Provisioning Manager data into Rational Quality Manager."

Any thought?

Thanks in advance
*piero