Like on this line here ?

$oPDF.set_info = "Creator", "hello.vbs"

idk - just a guess - based on the name of the "member" ... "set_info", sounded like a method, not a property - properties usually don't have "set" as part of the property name (but you never know). Plus the dead give-away was that this line had multiple params, which properties (usually) never have.