Object(static ot dynamic) doesnt cast shadows

Hello everybody, my foliage (trees) have dynamic shadows and biuldings have static. My directional light has on casting dynamic shadows, but I got error message “Performance Warning InstancedPoliageActor_0 Large actor receives a pre-shadow and will cause an extreme performance hit unless bCastDyanamicShadow is set to false.” I try change directional light type (static, station or movable) but no profits.