Including another robot part via xacro

Hi, I've been trying to attach a gripper to my manipulator and I've decided it would be best for my project if it was in another file. The problem is that I can't seem to do this correctly, when running the gazebo simulation I get the message Error [parser_urdf.cc:3474] Unable to call parseURDF on robot model Error [parser.cc:342] parse as old deprecated model file failed. [INFO] [1511876200.859116, 10.141000]: Spawn status: SpawnModel: Entity pushed to spawn queue, but spawn service timed out waiting for entity to appear in simulation under the name Kuka_kr3 And the robot will not spawn. Below I attach the codes for robot and gripper. Another question that I have, is that I've made these files in similar fashion, but I don't know if I can use the macros defined in the manipulator file in gripper definition? So far, I've written it as a standard urdf file. Manipulator file /kuka_kr30.50.5Gazebo/${color}transmission_interface/SimpleTransmissionhardware_interface/EffortJointInterfaceEffortJointInterface1--> Gripper /gripper0.50.5Gazebo/Orange0.50.5Gazebo/Red0.50.5Gazebo/Redtransmission_interface/SimpleTransmissionEffortJointInterfaceEffortJointInterface1transmission_interface/SimpleTransmissionEffortJointInterfaceEffortJointInterface1