X-Plane 12 crash when i press the toggle sling load button

Hello, when i try to sling a crew member, i have a crash with this error message :

Please make sure a load is attached when you trigger the function. This is a bug in X-Plane that has nothing to do with the EC 135.

I can't select any object because when i select an object the game crash

So when will the crash happen? When attaching the load or when toggling the load? Those are two different things.

First you have to attach an object (Add Sling Object in the EC 135 menu oder Weight and Balance from X-Plane - it's the same), then you can use the toogle button (Drop / Pick-up Load in the EC 135 menu oder Toggle Sling Load command from X-Plane - also the same). If you toggle without an object being assigned, X-Plane crashes with a "flight model error" and the message you posted. Only Austin himself probably knows what this message means. But the problem can be reproduced with any aircraft. It's a X-Plane bug. 

Update your EC 135. XP12.0.8 or newer needs V5.23.