How to understand Turtlebot + Phantomx urdf build error message

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As I too have a Phantomx Pincher Arm and Turtlebot(create), and am exploring cdrwolfe's phantomx package defined in http://answers.ros.org/question/10242... . So that I can use urdf_to_graphix to get a visual urdf, I encountered a parsing error msg doing a check_urdf on the phantomx.urdf as well as the same error msg creating a new urdf with xacro.py.

"Error:   Failed to build tree: parent link [plate_top_link] of joint [arm_base_joint] not found.  This is not valid according to the URDF spec. Every link you refer to from a joint needs to be explicitly defined in the robot description. To fix this problem you can either remove this joint [arm_base_joint] from your urdf file, or add "<link name="plate_top_link" />" to your urdf file.
         at line 226 in /tmp/buildd/ros-hydro-urdfdom-0.2.10-3precise-20140303-2236/urdf_parser/src/model.cpp
ERROR: Model Parsing the xml failed."

The <!-- joints -- > part of the phantomx_macro.xacro file for the arm_base_joint lists a <parent link="plate_top_link" which does not appear anywhere else in the phantomx_macro..xacro.

</link>
      <!-- joints -->
      <joint name="${prefix}arm_base_joint" type="fixed">
         <origin xyz="${M_SCALE*14.5} ${M_SCALE*0.2} ${M_SCALE*0.2}" rpy="${M_PI*0} ${M_PI*0} ${-M_PI/2}" />
         <parent link="plate_top_link" />
         <child link="${prefix}arm_base_link"/>
         <axis xyz="0 1 0" />
      </joint>

What else must I include in my process to generate the visual complete arm urdf? I very much look forward to further exploring this very comprehesive package and watching further development so that I can get my Pincher Arm up and running in Hydro with basic arbotix_gui then learning to use MoveIt!. Ross