roslaunch won't run node

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I have a node that I can run successfully using:

rosrun <package> <node_name>

In my particular case, my package is called "robot_arm" and node is "ReceiveOrder":

rosrun robot_arm ReceiveOrder

However, ReceiveOrder crashes when I try to run it via a launch file:

<launch>

    <rosparam command="load" file="$(find dispatcher)/dispatcher.yaml"/>
    <rosparam command="load" file="$(find robot_arm)/robot.yaml"/>

    <node name="ReceiveOrder" pkg="robot_arm" type="ReceiveOrder.py" output="screen"/>

</launch>

The error I get from running the launch file is as follows below. Why is this happening?

started roslaunch server http://HPLaptop:39521/

SUMMARY
========

PARAMETERS
 * /motion_planning/orient_tolerance: 0.05
 * /motion_planning/planning_engine: LBKPIECEkConfigDe...
 * /motion_planning/position_tolerance: 0.05
 * /motor_controller/num_motors: 6
 * /motor_controller/rate: 50
 * /order_timeout: 60
 * /robot/feedback_rate: 10
 * /robot/robot_id: 1
 * /robot/robot_timeout: 20
 * /rosdistro: indigo
 * /rosversion: 1.11.19

NODES
  /
    ReceiveOrder (robot_arm/ReceiveOrder.py)

ROS_MASTER_URI=http://localhost:11311

core service [/rosout] found
process[ReceiveOrder-1]: started with pid [13096]
[ReceiveOrder-1] process has died [pid 13096, exit code -11, cmd /home/altemir/ar01/src/robot_arm/src/ReceiveOrder.py __name:=ReceiveOrder __log:=/home/altemir/.ros/log/a6ba0c8e-3cda-11e6-a0d0-002315aba7e4/ReceiveOrder-1.log].
log file: /home/altemir/.ros/log/a6ba0c8e-3cda-11e6-a0d0-002315aba7e4/ReceiveOrder-1*.log
all processes on machine have died, roslaunch will exit
shutting down processing monitor...
... shutting down processing monitor complete