This isn't a problem with the itemtype. If you read the error then you try to access an index that is out of an array.
Let's say we got an array on the size of:
Code:
int[] array = new int[5];
Then if we do this:
Code:
int value = array[10];
We'll get that exception because there is not 11 indexes in the array, but only 5. Arrays are 0 indexed, so 0, 1, 2, 3 & 4 would work in our case.
But if you really want a new itemtype then it is in your client in the ini folder. For a datcryptor just search there is released a few.