HI , I setup moveit for my simple urdf. I get this error although I have setup kin. chain while creating group.

All is well! Everyone is happy! You can start planning now!

[ INFO] [1437491541.950725317]: Loading robot model 'myfirst'...
[ INFO] [1437491542.102668136]: Loading robot model 'myfirst'...
[ERROR] [1437491542.103025494]: Group 'right_arm' is not a chain
[ERROR] [1437491542.103109791]: Kinematics solver of type 'kdl_kinematics_plugin/KDLKinematicsPlugin' could not be initialized for group 'right_arm'
[ERROR] [1437491542.103519521]: Kinematics solver could not be instantiated for joint group right_arm.
[ INFO] [1437491542.153130872]: Starting scene monitor

myfirst.srdf

<?xml version="1.0" ?>

<robot name="myfirst">
    <group name="right_arm">
        <chain base_link="base_link" tip_link="x-carriage" />
    </group>
    <group_state name="home" group="right_arm">
        <joint name="gripper_extension" value="0" />
    </group_state>
    <group_state name="end" group="right_arm">
        <joint name="gripper_extension" value="8.6" />
    </group_state>
    <group_state name="mid" group="right_arm">
        <joint name="gripper_extension" value="4.3966" />
    </group_state>
    <virtual_joint name="base" type="fixed" parent_frame="odom" child_link="base_link" />
    <disable_collisions link1="base_link" link2="x-carriage" reason="Adjacent" />
</robot>

basic_shape.urdf

<?xml version="1.0"?>
<robot name="myfirst">
      <link name="base_link">
        <visual>
          <origin xyz="4.5 0 0" rpy="0 0 0" />
          <geometry>
            <box size="9 .2 .2" />
          </geometry>
          <material name="blue">
            <color rgba="0 0 .8 1"/>
          </material>
        </visual>
      </link>

      <link name="x-carriage">
        <visual>
          <origin xyz=".2 0 0" rpy="0 0 0" />
          <geometry>
            <box size=".4 .4 .4" />
          </geometry>
          <origin  xyz="0.1 0 0"/>
          <material name="Gray">
            <color rgba=".7 .7 .7 1"/>
          </material>
        </visual>
      </link>

      <joint name="gripper_extension" type="prismatic">
        <parent link="base_link"/>
        <child link="x-carriage"/>
        <limit effort="1000.0" lower="0" upper="8.6" velocity="0.5"/>
        <origin  xyz="0 0 0"/>
      </joint>

</robot>