"error while assembling"

When i have edited a preset, bought all needed pieces and try to auto assemble them, i get this error message.

I hope anyone can help me to solve this problem.

Best regards and cheers

Hey CWX thx a lot but just figured it out that one part of the Weapon wasn`t discovered...after that it worked as it should. So it was MY fault and not the fault of a mod, the game or something else.

Thx for trying to help me

PS: How can i mark this topic as solved and close it?

Best regards