I am experiencing what could be a glitch in the game, there was an older post on this forum which described the same problem-
"I have just solved the first puzzle in Cedar Ward (during the Melissa section of the game), obtained the key, unlocked the stairwell door and descended the stairs, when I try to open the door at the bottom of the stairs it looks as though I fall through blue sky (I know how crazy that sounds) and I get the message asking if I want to try again. It then brings me back to the checkpoint just inside Cedar Ward - has anyone else experienced this?"
I have replayed the stage numerous times and always the same outcome ? has any one else had this apart from me and the above post.
The previous poster said it resolved itself after replaying the stage several times, I have also quit game and restarted PS3- still the same,