[Samba] Upgrading Samba on Debian

[Andy Pont]

Hello,

I have a server running Debian 11 into which was installed Samba 4.15.7 
from http://apt.van-belle.nl/debian/.  Apt now has access to the 
bullseye-backports repo but when I run apt-get update and apt-get 
upgrade I don’t see Samba in the list of packages that can be upgraded 
despite 4.16.4 being in backports.

Is there some magic incantation that I am missing?

-Andy.