Slider diagram image not update when export

edit

I used the following code to export the image of the slider diagram with my GUI open. But the image never update whatever I did to modify the case and slider diagram(trip lines, etc..). It seems It doesn't make any difference whether I open the case or not, the output slider diagram image always keeps the same. I tried psse 35 and 34 both do not work. Could someone give me any idea why it happens? Thanks a lot!

psspy.case(r"""case1""")
psspy.opendiagfile(r"""slider.sld""")
psspy.exportimagefile(3,r"""figure1.png""", 100)
psspy.closediagfile()
psspy.case(r"""case2""") # case2 has extra line outage
psspy.opendiagfile(r"""slider.sld""")
psspy.exportimagefile(3,r"""figure2.png""", 100)
psspy.closediagfile()