Cannot make player enter vehicle

so, I was coding earlier, creating a spaceship for my game in UE4. I was making the code for my third person character to swap, however, when I went to possess, the ship was an imcompatible reference. Any ideas? It’s an actor, just like the character, it’s bound to the flight game mode.
if I try to connect it to something else, e.g. my companion A.I, it is fine, just that one.