Package update problem...

[Mark Neidorff <mark@neidorff.com>]

I'm running Jesse 8.6 with a KDE desktop.

I get a desktop notification that there is one or more package updates 
available.  I select the package(s) and then I'm asked for authentication. I 
type in the root password, but it is rejected.  I also try my user password, 
but that is also rejected. (Tried multiple times, so it doesn't seem to be a 
typo problem)

If I go to the command line--as root--and do apt-get update and upgrade, then 
the update installs correctly.

This sounds like something easy to fix, but I just don't know where to fix and 
what fix to apply. Please let me know.

Thanks,

Mark