[Samba] Error loading module '/usr/lib/samba/pdb/tbdsam.so'

[Bob Wooden]

Brief history, originally setup as Ubuntu 7.10. Upgraded to 8.04.1LTS,
Samba 3.0.28 and has latest updates installed as of this morning.
Currently Samba is configured to use smbpasswd for passdb backend. As
tdbsam has become the peferred backend, would like to migrate to tdbsam.

When I attempt "pdbedit -i smbpasswd -e tbdsam" I get the following
result: "No builtin backend found, trying to load plugin    Error
loading module '/usr/lib/samba/pdb/tbdsam.so':
/usr/lib/samba/pdb/tbdsam.so: cannot open shared object file: No such
file or directory   No builtin nor plugin backend for tdbsam found   
Unable to initialize tbdsam."

The directory /usr/lib/samba contains only vfs directory. So, indeed
there is nothing to open there. I tried to "locate" tdbsam.so but Ubuntu
returns no location, so I do not believe it appears to be loaded.

How do I fix this issue so I can migrate?