If only the PWE and ENET LED are flashing then usually this means the AP does not have an IP address. Have you tried attaching a console cable to see if there is any output? This will give you information on IP addressing and the master election status.
Attach the console cable to one of the new AP's and also provide the tech support from the working Virtual Controller as well.
Is your Virtual Controller configured to allow any new AP's to join or only certain MAC addresses?