If the disk was previously used as part of a RAID volume there may still be some metadata on the disk. Look for things like "foreign" configs, these are part of the old metadata. Clear those. Make sure the controller detects the disk as "Unconfigured Good". This means it's "clean" and ready to be configured. If the controller has any RAID functionality but you're not using it configure the disk (or the whole controller) for JBOD.