Error: Joint is missing a parent and/or child

Hi all, I'm trying to build a robotic arm, but I'm having troubles when I create the macro to simplify the code. I have the next error: Failed to build tree: Joint [module_1_length_yaw_joint] is missing a parent and/or child link specification. I have try to solve it modifying the code as many times I imagine it could works, but anyway it didn't work. This is the part of my code for the macro: Gazebo/Orange I try many changes creating the name for the child in the joint, but I don't know if I missing something in the if statement for the xacro language. If you need more information I can update the question. Thank you for your help. Jorge NOTE: I try to ask this question in Gazebo answers, but it says that is SPAM and doesn't publish the question