Restitution coefficient does not change

Hi all, I'm trying to change the restitution coefficient in Gazebo7, but still I can't make it. My URDF code is here: Ball: 0.1 0.1 0.10.1 0.1 0.10.50.01 Target: 0.1 0.1 0.10.1 0.1 0.10.50.01 And gazebo.xacro is here: Ball: true10.00.01 Target: true10.00.01 When I perform this simulation, both two objects' restitution coefficient are still 0, and they start bounding in the world. I would really appreciate you if you would give me some advice.