including model.sdf in .world Gazebo7

Hi, im working since a couple weeks with gazebo and I have some problems including a model.sdf into a .world file. I am using Gazebo7 and ROS-kinetic. I already sourced the MODEL_PATH at the .bashrc file export GAZEBO_MODEL_PATH=/home/MyComputer/sim_ws/src/sim_sdf/models/vehicle/:$GAZEBO_MODEL_PATH and the simulation is running when I start the model-file on its own. After testing I reduced the model-file: ....... To include the model into the world file I use following command: model://ground_planemodel://sunfalsemodel://vehicle/model.sdf 0 0 1 0 0 0 the problem is that gazebo is starting without a model and inside the terminal appears Directory doesn't exist[/home/MyComputer/sim_ws/src/sim_sdf/models/vehicle/model.sdf] So I tried to use model://vehicle/model that will take ages and still not work or model://home/MyComputer/sim_ws/src/sim_sdf/models/vehicle/model what also wont work..... Hopefully there is somebody who had a similar problem and know what to do. I am totally stucked. Thank you in advance