Proper .xinitrc to start Mate

I am seeing errors that indicate that Mate is not properly starting. For
example, if I try running mate-power-manager from a terminal window, I get:
{mate-power-manager:78756): PowerManager-WARNING **: 19:28:45.974: Failed
to connect to socket /var/run/dbus/system_bus_socket: No such file or
directory

Indeed, the directory is empty. And:
error: XDG_RUNTIME_DIR is invalid or not set in the environment.
These should be started when Mate starts and have been in the past.

My .xinitrc just contains contains:
xset fp rehash
exec ck-launch-session dbus-launch --exit-with-session mate-session

I do see three dbus processes running:
2538  -  Is       0:37.32 /usr/local/bin/dbus-daemon --syslog --fork
--print-pid 5 --print-address 7 --session
 2541  -  S        0:41.18 /usr/local/bin/dbus-daemon
--config-file=/usr/local/share/defaults/at-spi2/accessibility.conf --nofork
-
 2537 v0  I        0:00.00 dbus-launch --exit-with-session mate-session

I've looked around a bit, but don't see anything that I need to add.
Cluebat would be appreciated.
-- 
Kevin Oberman, Part time kid herder and retired Network Engineer
E-mail: rkoberman@gmail.com
PGP Fingerprint: D03FB98AFA78E3B78C1694B318AB39EF1B055683