Magnavox H2160MW9 VHS tape "recording not allowed" to hard drive

I am converting my out of production (1972-2001) tapes to DVD before they degrade and assume they were produced with copy protection in force and the tapes are typically two volume sets. For various tape sets I have copied both, one or neither of a set of tape volumes to the unit's _hard_disk_drive_ and received the message "recording not allowed" for neither, one or both tapes, respectively. Is there an explanation for this random "recording not allowed" message? Is there a work around or upgrade to the systems bios, firmware or software that can be applied? For good measure, I feed the VCR video output through a signal amplier to prevent the dark oscillations that occur on copies of tapes with copy protection. Thanks in advance for any guidance on this problem.