[dvd::rip] error encountered in transcode - dvdrip 0.97.4

[Kenneth Ng <kenneth.d.ng@xxxxxxxxx>]

When I try to transcode the DVD Tarzan (so my son can watch it on his
computer, that does not have a dvd drive), I get a message that:

job 'Multiplexing MPEG - title #1' failed.
Executed command: dvdrip-exec mplex -f 4 -V -o .....

There is an error message that it ws unable to read file
.../tarzan-001.m2v.  The file exists, but is zero bytes in size.

I'm a little new here, what other information is needed to help diagnose this?