Hello everyone

I have a base frame (I've simplified the model) which will accommodate some mechanical equipment on top and I want to simulate the deflection during the lifting stage. The base frame will be lifted from four points where a lifting lug will be bolted. I wanted to simulate the lifting operation by assigning the bolt holes as hinged support but I'm getting an error that the model is unstable. Isn't a hinge connection an immovable connection which allows only rotation?