Certain B9 and Firespitter parts cause my craft to glitch out

[Chel]

I installed B9, built a craft, and used the B9 wings. Next minute, when I launched it, the wings immediately dropped off (not due to weight, as it was a very light plane), and the craft is sent at lightspeed to somewhere unknown. Removing the wings fixed this. With Firespitter, again, it was the wings, but this time, the plane became uncontrollable, veering to the right and my controls not responding. Removing the wings and using stock ones again fixed the problem. So I ask the question, why when I've successfully installed the mod, and have the latest version, do some parts glitch out and others don't?