It's not in the PRINCESS's room, it's in the dungeon below the library.
You get the chese for a mouse in the left room in the destroyed castle in astro knights in poptropica
Find the old cheese. . Give the cheese to the mouse and give the mouse to the owl.
you put it in the room with the mouse in the astro knights castle and the mouse will eat it
She the PRINCESS is on a asteroid being held hostage by Morder
If you mean Poptropica, you can get the rat when you go to the castle and go to the left door, give the Moldy Cheeseto the rat, and he will come to you.
go into the dungeon
You Get Cheese
PROSSESSING ROOM
You go to the library after you get the book slip from the man in the museum. you click on the shelf marked with McM. the floor will pop open. you go down the stairs and go in the small room, there lay the cheese on the table.
There is no cheese in the Haunted House game. (see the related question)
say cheese is right by Saltty's in big nate
go into the all the rooms in the castle and in on room on the book-shelve there will be something white. click on it stairs will come go down and there's the cheese gavin