Cristovin

Good afternoon, Im trying to build a space station, and i built the space shuttle and placed part of my SS inside of it, my problem is when Im in orbit and i want to decouple what is inside of the cargo but im not able to, i tryied everything, tryied to put some decouplers and other stuff but nothing handled it, the game still recognizing the cargo and part of the SS as the same thing, what to do??