Nice Prowler. ;)

ohhh now i understand you cant use projectors for sub grids. you would have to use a merge block to connect the turret to the tank in creative than take a blueprint of the tank with the connected turret than try again. once you build the tank in survival you remove the merge block than it should work.

Are you using creative mode? I use a projector in survival, writes does not support components.

hmmmmmm try reloading SE, i have never had this problem. i will see if i can figure out what is happening i will get back to you if i find a better solution.

I have a problem, when I put your building plan, the lower part is there, but the tank turret does not appear.