If you are netlisting out to PADS then it may well be the lack of the PARTS property, if it is Expedition then you will need to provide more information on how you've mapped this in the Central Library, Expedition doesn't use the PARTS property.
OK, thank you Robert.
I am going into Expedition for PCB.
The library controls on our system mean that I currently cannot write to the central library. As far as I can see, the parts are only stored as local parts to the design. If I open the library manager, I can see that a new partition has been created using the name of the board, but it is empty.
I am a new user to Mentor, so apologise for any ignorance about the library system.