The command fails because no drives of the specified drive class in the appropriate drive state are available to create the full array.
Some drives might be available, but not all of the required drives.
Perhaps some drives are not in the candidate state.
Perhaps an enclosure might be offline.
After correcting the drive availability problem for the proper class, use the lsdriveclass command or the lsdriveclass view in the GUI to verify the number of available drives. Then try the command again.