Spawning Erratic robot in Gazebo 1.9 with ROS groovy

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Hi, I am trying to spawn erratic robot in Gazebo 1.9 using following launch file.

<launch>
<!-- Convert an xacro and put on parameter server -->
<param name="robot_description" command="$(find xacro)/xacro.py $(find erratic_description)/urdf/erratic.urdf.xacro" />

<!-- Spawn a robot into Gazebo -->
<node name="spawn_urdf" pkg="gazebo_ros" type="spawn_model" args="-param robot_description -urdf -model erratic" />
</launch>

It works perfect for PR2 robot but in the case of erratic it does not spawn the robot. Any suggestions? Thanks. Here is the output of the launch file. Running PR2 in same way also generates alot of errors in terminal but manage to spawn it.In this tutorial they explicitly says that

Note: at this writing there are still a lot of errors and warnings from the console output that need to be fixed from the PR2's URDF due to Gazebo API changes.

Warning [parser.cc:353] No <sdf> element in file[data-string]
Error [parser.cc:694] XML Element[controller:diffdrive_plugin], child of element[model] not defined in SDF. Ignoring.[model]
Error [parser.cc:685] Error reading element <model>
Error [parser.cc:345] Unable to read element <sdf>
Error [parser.cc:296] parse as old deprecated model file failed.
Error [World.cc:1469] Unable to read sdf string
<!--This document was autogenerated by xacro from /opt/ros/groovy/stacks/erratic_robot/erratic_description/urdf/erratic.urdf.xacro | -->
<!--EDITING THIS FILE BY HAND IS NOT RECOMMENDED========== -->
<robot xmlns:controller="http://playerstage.sourceforge.net/gazebo/xmlschema/#controller"
    xmlns:interface="http://playerstage.sourceforge.net/gazebo/xmlschema/#interface"
     xmlns:sensor="http://playerstage.sourceforge.net/gazebo/xmlschema/#sensor" name="erratic">

<!-- Included URDF Files -->
<material name="Black"><color rgba="0.0 0.0 0.0 1.0" /></material>
<material name="Blue"><color rgba="0.0 0.0 0.8 1.0" /></material>
<material name="Green"><color rgba="0.0 0.8 0.0 1.0" /></material>
<material name="Grey"><color rgba="0.7 0.7 0.7 1.0" /></material>
<material name="Grey2"><color rgba="0.9 0.9 0.9 1.0" /></material>
<material name="Red"><color rgba="0.8 0.0 0.0 1.0" /></material>
<material name="White"><color rgba="1.0 1.0 1.0 1.0" /></material>
<link name="base_footprint">
<inertial><mass value="0.0001" /><origin xyz="0 0 0" />
<inertia ixx="0.0001" ixy="0.0" ixz="0.0" iyy="0.0001" iyz="0.0" izz="0.0001" /></inertial>
<visual><origin rpy="0 0 0" xyz="0 0 0" /><geometry><box size="0.001 0.001 0.001" /></geometry>
<material name="Green" /></visual><collision><origin rpy="0 0 0" xyz="0 0 0.128" /><geometry>
<box size="0.001 0.001 0.001" /></geometry></collision></link>
<joint name="base_footprint_joint" type="fixed"><origin rpy="0 0 0" xyz="0.063 0 0.128" />
<parent link="base_footprint" /><child link="base_link" /></joint>
<link name="base_link"><inertial><mass value="20" /><origin xyz="0 0 0" />
<inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0" /></inertial>
<visual ...