custom_node not launching

edit

Hi, all I have ubuntu 16.04LTS and ROS1, I am working on ur5, I am trying to create a launch file which will include my pythons executable the following is my launch file

?xml version="1.0"?>

launch>

arg name="gui" default="True" />

param name="robot_description" command="$(find xacro)/xacro --inorder $(find ur5_description)/urdf/ur5_robotiq85_gripper.urdf.xacro" />

node name="my_joint_state_publisher" pkg="ur5_description" type="my_joint_state_publisher.py" />

node name="robot_state_publisher" pkg="robot_state_publisher" type="state_publisher" />

node name="rviz" pkg="rviz" type="rviz" args="-d $(find ur5_description)/config/ur5.rviz" required="true" /> /launch>

but this gives me the following error: cannot launch node of type [ur5_description/my_joint_state_publisher.py]: can't locate node [my_joint_state_publisher.py] in package [ur5_description]

my pkg name is correct and my python file is an executable file check then twice. What could be the reason of this error?