UR5 robot loads into Gazebo but acts to move randomly.

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I am a Beginner in ROS, Gazebo. I have tried to attach Intel RealSense cam as an end effector for the UR5 from this post.

I have followed the process of setting up ur5 using moveit tutorial.

I am using ROS Kinetic and Gazebo 9.13.

My Problem: When I launch the gazebbo_demo.launch file, the UR5 moves in an unexpected manner and Falls down. Why is this happening?

Can you point out what is wrong with the way I am adding the camera to the robot's link or making something wrong with moveit setup?

launch file: link

C:\fakepath\gazebo_ur5_dead.png

It shows some errors and warnings as show here.

link to URDF file.

Thanks in advance.