[Haskell-beginners] index too large

[Nathan M. Holden]

I've been working on a quick program that acts (vaguely) like a console, lets 
me type notes and outputs them in a .tex file. I figure it's not that 
complicated, but it uses a vaguely n-ary structure, so that I can have headers 
and sub-notes, which loos like:

data Note = N {
  nTitle  :: {Char},
  nBody :: {Char},
  nFormat :: Format,
  subs :: [Note]
| E [Char]

Format's just a collection of preset formats, so I don't have to dynamically 
handle that (since I didn't need to for my uses).

Anyways, for whatever reason, sometimes while adding notes, it sends me an 
error: Prelude.(!!): index too large

My only 2 uses of that are in 
getFullName :: [Note] -> [Int] -> [Char]
getFullName d [] = "/"
getFullName d (x:xs) = "/" ++ getPartName (d!!x) ++ getFullName (subs (d!!x)) 
xs

and

moveIn :: [Note] -> [Int] -> [Char] -> Int -> [Int]
moveIn [] i m c = reverse i
moveIn ((N dt db df du):ds) [] m c = if matchNote (N dt db df du) m then c:[] 
else moveIn ds [] m (c+1)
moveIn n i m c = last i : ((moveIn (subs (n!!(last i)))) (allButLast i) m 0)

where the [Int] is the variable I use to track where in the tree I am. Since 
I'm not moving into a Note that doesn't exist, and the display shouldn't be 
changing, what could be the problem?

This is probably too in-depth a question, now that I think about it...