Help with fixed joints

I’m trying to use joints to lock two objects together so when one moves so does the other, and vice versa. But I’m having some issues. I tried adapting the example to my program like this

physics.create_joint(physics.JOINT_TYPE_FIXED, "A1#collisionobject", "A1joint", vmath.vector3(0, 0, 0), "CoMass#collisionobject", vmath.vector3(0, 00, 0), { max_length = 0 })

This code is located in the init function of a script that is located in a game object separate from either of the objects I reference in the code, however I did try it like that with this code being in the init function of one of collision objects I am referencing with joints and it made zero difference.

If these joints work how I think they work then both objects should constantly try to have a zero distance from each other (eventually I want to change this so they always maintain the same relitive position and distance to each other, but one thing at a time), however instead nothing happens as if I had never written the code at all. When one of the objects moves the other one just stays still and in the same place. What am I doing wrong and am I even using the right thing to achieve the effect I want to achieve ( where if one object moves 10 steps over so will the other one) ?

Is your project small, could you zip it up and share it here?

Are you getting any errors in the console?
Are the collision objects dynamic?

[Edit] There’s no problem with that line of code (with tweaked names anyway). Something else must not be set right in your project. Using max_length = 0 works as you would expect.
Defold Fixed Joint.zip (2.9 KB)