URDF prismatic joint on 2 axis

Hi all.
I have an URDF robot model in GAZEBO with a camera and i wanna move the camera on two axis Y,Z.
I know that i have to use the prismatic type, but i cant figure out how to set it. I've tried to create two joints between the base_link and the camera_link one for the Z slide and the other one for the Y slide but it gives me errors [ERROR] [1447412621.880447632, 1337.300000000]: Tried to advertise a service that is already advertised in this node [/tablet_camera/set_parameters] [ERROR] [1447412621.989409540, 1337.300000000]: Tried to advertise a service that is already advertised in this node [/tablet_camera/image_raw/compressedDepth/set_parameters] [ERROR] [1447412622.090016972, 1337.300000000]: Tried to advertise a service that is already advertised in this node [/tablet_camera/image_raw/compressed/set_parameters] [ERROR] [1447412622.263917910, 1337.300000000]: Tried to advertise a service that is already advertised in this node [/tablet_camera/image_raw/theora/set_parameters] [ERROR] [1447412627.912015293, 1337.300000000]: This robot has a joint named "camera_joint_y" which is not in the gazebo model. [FATAL] [1447412627.912106858, 1337.300000000]: Could not initialize robot simulation interface This is the code in my xacro file relative to the camera joints transmission_interface/SimpleTransmissionEffortJointInterfaceEffortJointInterface1transmission_interface/SimpleTransmissionEffortJointInterfaceEffortJointInterface1 And this is the plugin inside the xacro 30.01.3962634800800R8G8B80.02300gaussian0.00.007true0.0tablet_cameraimage_rawcamera_infocamera_link0.070.00.00.00.00.0 Of course I've created the position controllers yaml file etc etc for the controller manager