Charles Decatur

So far I love this game but I seem to be stuck. i almost never get stuck so I'm mostly worried that something is wrong because many cave openings in the game either won't do anything when I enter or a load error message appears. I'm basically at the castle in the tree that you get to by walking across the water. The castle is a dead end although I did manage to walk up the wall at the door but then I can't see my character. My question is what do I do there? Thanks.