Symmetric Stress ,Without Fixed Constraint

Hi guys,

I have a symmetric structure which is imposed by symmetric stresses , and i wanna know the displacement of top point of this model without any fixed constraints.

But it cannot be solved ,says
"Failed to find a solution.
The relative error (2.8) is greater than the relative tolerance.
Returned solution is not converged.
- Feature: Stationary Solver 1 (sol1/s1)".

Does anyone have any experience on this kind of model? I don't wanna add fixed constraints, cause it is the most similar one to real situation. Is it possible?

Thanks for any help.
Emma