Can't use slidebar of joint_state_publisher window in Rviz
I've created a xacro file for my robot arm and successfully visualized it in Rviz with the display.launch launchfile from the urdf_tutorials package. However, i can't slide left or right with the slidebar to control the joint movements in the joint_state_publisher GUI window, the only thing I can click is the randomize button below the slide bars. The robot is then moving accordingly, so I think there is no problem with my xacro file.
I have to mention though that I haven't included collision and inertia tags in the xacro file yet, could this be the reason?
Can anyone tell me why I can't use those slidebars, or how I can fix this problem? Thanks a lot!! :)