stress constraint in topology optimization

Hello,

I am trying to perform a topology optimization with objective minimizing the volume. It is a HEX mesh. i have a couple of responses and constraint on displacements. I also set a stress constraint of 1050 MPa. When i run the analysis the .out file says 'stress constraint inactive' and i get stresses of 2000 - 3000 MPa. Why is this possible when is set a stress constraint? Is there a way to perform a topology optimization with an active stress constraint?

PS. i created the stress constraint via topology ==> paramters ==> stress constraint