impossible to decrease ticken in static load simulation

Hi,

with a thickness of 0.5mm analys ok , 0.3 ok and then 0.2 this :

it seems 0.28569mm is the lower limit without error so I don't really understand why; I ve tried to modifiy the part or the load force or material in order to see if it is that but it was not ????

Thanks by advance

SolidworksSimulation