roslaunch error - "ERROR: cannot launch node of type"

edit

When using a launch file in groovy catkin package, roslaunch reports an error:

ERROR: cannot launch node of type [nao_driver/nao_camera_both.py]: nao_driver
ROS path [0]=/opt/ros/groovy/share/ros
ROS path [1]=/home/ludo/workspace/catkin_ws/install/share
ROS path [2]=/home/ludo/workspace/catkin_ws/install/stacks
ROS path [3]=/home/ludo/workspace/catkin_ws/src
ROS path [4]=/opt/ros/groovy/share
ROS path [5]=/opt/ros/groovy/stacks

The contents of the launch file

<node pkg="nao_driver" type="nao_camera_both.py" name="nao_camera_both" required="true" args="--pip=$(arg nao_ip) --pport=$(arg nao_port) fps=5" output="screen">
        <param name="camera_switch" type="int" value="1"/>
        <param name="fps" type="int" value="1"/>
                <!--
                Image quality constants
                        k960p = 3                # 1280*960
                        k4VGA = 3                # 1280*960
                        kVGA = 2                 # 640*480
                        kQVGA = 1                # 320*240
                        kQQVGA = 0               # 160*120
        -->
        <param name="quality" type="int" value="3"/>
        <param name="topCamParams" type="string" value="package://morris_simulation/config/topCamCalibSim.yml"/>
        <param name="bottomCamParams" type="string" value="package://morris_simulation/config/bottomCamCalib.yml"/>
  </node>

rosrun nao_driver nao_camera_both.py works well though.