re-apply changes by rtagging older versions...

[z5h]

I'm trying to RE-APPLY, to cvs HEAD, changes made to a  between dates
date0 and date1. cvs update wond work with dates, so I have to tag
historic versions.

I was doing something like this, but it's doesn't seem to be working as
I expect. Can anyone see a problem?
I have looked very hard at cvs history to determine the exact times
that mark the changes I want.
Somehow I don't end up getting them. Am I confused as to how rtag with
a -D works?

cvs -d ... rtag -D "date0" redo_mb_0 project
cvs -d ... rtag -D "date1" redo_mb_1 project

cvs -d ... co project
cd project

cvs update -jredo_mb_0 -jredo_mb_1