why is that my simulation data value is not present in my constraints tab when i use design optimization

I'm Designing a bio-gas scrubber and i had an issue, could you please help me about this issue, i would like to optimized the copper rod but the simulation data is not available when i add my constraints in the design study but in my static analysis in the sensor  tab the stress value is present.

Or i can just manually type the value of the minimum or maximum stress

I attached picture of my design study and static analysis.

SolidworksSimulation