Can anyone help me this error for gazebo?

edit

I type these commands-

export TURTLEBOT3_MODEL =waffle
roslaunch turtlebot3_gazebo turtlebot3_house.launch

I get this error-

Invalid <param> tag: Cannot load command parameter [robot_description]: command [/opt/ros/kinetic/lib/xacro/xacro --inorder /home/vivek/catkin_ws/src/turtlebot3/turtlebot3_description/urdf/turtlebot3_waffle.urdf.xacro] returned with code [1]. 

Param xml is <param command="$(find xacro)/xacro --inorder $(find turtlebot3_description)/urdf/turtlebot3_$(arg model).urdf.xacro" name="robot_description"/>
The traceback for the exception was written to the log file