Gazebo SDF has no gazebo element

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I am new to ROS and Gazebo.

I'm running through the "Gazebo ROS API for C-Turtle" tutorial and receive the following error:

Warning [parser.cc:332] Gazebo SDF has no gazebo element
Warning [parser.cc:271] parse as sdf version 1.0 failed, trying to parse as old deprecated format
Warning [parser.cc:277] parse as old deprecated world file failed, trying old model format.
Exception [ODELink.cc:317] Setting custom link desk1mass to zero!

terminate called after throwing an instance of 'gazebo::common::Exception'
Aborted (core dumped)
[empty_world_server-2] process has died [pid 2568, exit code 134, cmd /opt/ros/fuerte/stacks/simulator_gazebo/gazebo/scripts/gazebo /opt/ros/fuerte/stacks/simulator_gazebo/gazebo_worlds/worlds/empty.world __name:=empty_world_server __log:=/home/joe/.ros/log/4410c96e-bc79-11e1-b83e-00269ed0509d/empty_world_server-2.log].
log file: /home/me/.ros/log/4410c96e-bc79-11e1-b83e-00269ed0509d/empty_world_server-2*.log

In the terminal where I issued the spawn command, I receive a "successfully spawned model" message. However, I receive the above error and do not see a model in the world map. (does that last bit have to do with the desk1mass being set to 0?)

Do I have the incorrect version of Gazebo (Diamond back release as it's "recommended") installed with ROS? I am running the most up to date version of ROS (12.04 on Ubuntu).

Thanks for the help.