Gazebo SDF model loading in Groovy

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I have a correct Gazebo 1.2 http://pastebin.com/Q0nLVDLa (model), slightly modified from the http://gazebosim.org/wiki/Tutorials/1.2/build_robot/mobile_base (Gazebo tutorial). If that model with it's manifest.xml is in ~/.gazebo/models, then Gazebo of ROS can see and load this model.

Now I would like to load this model with the spawn_model script of ROS gazebo package.

I have tried this command:

rosrun gazebo spawn_model -gazebo -file /home/ronald/catkin_ws/src/gazebo_heightmap/Media/models/robot1/model.sdf -model myrobot

and tried with this launch file

<launch>
<param name="robot_model" textfile="$(find gazebo_heightmap)/Media/models/robot1/model.sdf" />
<node name="spawn_robot1" pkg="gazebo" type="spawn_model" args="-gazebo -param robot_model -model myrobot" respawn="false" output="screen" />
</launch>

In both cases, Gazebo node gives error messages

Error [parser.cc:675] XML Element[origin], child of element[model] not defined in SDF. Ignoring.[model]
Error [parser.cc:666] Error reading element <model>
Error [parser.cc:366] Unable to read element <gazebo>
Error:   Could not find the 'robot' element in the xml file
     at line 61 in /tmp/buildd/ros-groovy-urdfdom-0.2.6-1precise-20121225-1343/urdf_parser/src/model.cpp
Error [parser_urdf.cc:1659] Unable to call parseURDF on robot model
Warning [parser.cc:374] Gazebo SDF has no <gazebo> element in file[urdf string]
Error [parser.cc:318] parse as old urdf model file failed.
Error [World.cc:1190] Unable to read sdf string

To me it seems that the model description files must be different to load it with spawn_model, but how?

Update: The model does not contain <origin> element, as suggested. The model also loads if it is included in a world description file. Just the spawn_model does not work.