Make sure HM is spanker, not Ms Newman, and if it is anal scene, you need her OTK, not on desk.
"Order her to strip naked. position her w/ hands above her head, do a body search, take pictures. put her over the desk and spank her with paddle. put her over the knee and rub her vag.
select the headmaster the spank her while she straddles your lap. put her into diaper position and insert dildo. They wont seem fully maxed out but this is the correct method."
Another commenter submitted this, and it worked for me. Good Luck!