When I change demand position value , actuator does not respond demand value.it show only maximum position length value .Maximum position is 2.5mm.

I am using FEM based linear actuator. with close loop controller.Close loop controller consists of Position,Velocity and Current controller.when demand Position change from 2.5 mm to 2 mm, linear actuator does not respond .i do not know what kind of error error occured in model.