Create: Big Cannons Twin Autocannon Issue

https://reddit.com/link/1v6hvrg/video/4wcv61iqiffh1/player

I've been playing on my survival world. I did the basics to get my cannon parts - I've casted them, bored them, and made them as needed. However, whenever I place them correctly, it gives me an error message (shown in video). Why does this happen?