Panasonic DMR E75V DVD/VCR Dubbing from VHS to DVD Problem

I am attempting to dub a tape of old recorded TV shows onto a DVD. The protection lock has not been broken off the the tape. I have put the DVD and Tape in and followed the directions in the manual to a "T". But I get this message when I hit the Dubbing button: "Cannot Dub.Title is not recorded." There is no explanation of this in the rather poorly written manual. What does this mean? Can I dub this tape? I have dubbed other tapes; some with success; some without. Please help!