I'm using Sonic ReelDVD trying to get this film converted to the TS folders.

I have a lot of the files, but the program gave me an error message that said,
"Volume and Anchor files could not be created". This is not the first dvd I've ever authored with this software, but it is the first time I've come across this message.

What are the volume and anchor files and are they necessary for creating a dvd?