There's a bug in RTM version with creating attribute using WMI. You'll receive an error similar to the following:
"Verification failed with  errors:
: Failed to verify Discovery
This is an issue with the attribute creation UI.
Export the management pack. Add the reference to Windows Library in the <references> section at the top.
Try XML Notepad to do this. It breaks out the XML for readability.
Then, import the edited XML (management pack) and create the WMI attribute.