Optimal Power Flow option not installed

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Hi all, I try to test the savnw example case but when i read the savnw.rop file i get the message "Optimal Power Flow option not installed".

psspy.case(r"""C:\Program Files\PTI\PSSE32\EXAMPLE\savnw.sav""")
psspy.ropf(r"""C:\Program Files\PTI\PSSE32\EXAMPLE\savnw.rop""")

Should i use another option to read the files? Would be a problem with my PSS university licence?
Thanks a lot in advance