There's a bug (i think) when you do wicked game i think thats the name but it involves kates music room party and if you want to go there you are chaught then you re enter the school but when I interacted with the box in the admin wing nothing happend and then I tried the nurse office or anything other then the main stairs and still there was nothing I could do but go home. I got caught by the guard and I did get back in the school trough Maxine but yet still nothing that would progress that quest for me.
Hello again! First things first, I was unable to recreate a scenario in which I was locked out of completing the Quest, so let's see if we can figure it out. I'm assuming you talked to the nurse and didn't ask to borrow her costume, had you done so you should have found yourself carried (inside the box) to the party. If that is correct then the Nurse should have pushed you into her office in order to hide you from Kate and her friends, at which point you should no longer see the box in the hall. If that is what you did and you still see the box then it is a bug, however you may still be able to complete the Quest if you have a save and wish to try again. Just go into the Nurse's Office during that portion of the Quest and Interact with the bed and you will make your own costume which upon acquiring will disable the Guard and allow you into the upstairs and then the party. Hopefully this was of some use to you, good luck!