It's because the older version of Python has been officially retired and is no longer supported.  Now, if you still have your registration serial number for Poser 11 Pro, you can still upgrade to the current version of Poser 11.  This is the link: https://www.posersoftware.com/.  I have Poser 11, 12, and 13 installed on my rig, and Poser 11 is the updated version from SmithMicro's app.  A lot of users complained about the changeover but have since moved on.  If you can manage to update your Poser 11, keep it installed for the Python 2 script compatibility.  That's what I'm doing.