Problem with a simple C app. Calloc

I'm making this simple C program.  I'm using Calloc to allocate space to hold an array containing the number of instances of each letter in the file.
Source: http://pastebin.com/G46Pr6Tg

When I try to Calloc, or Malloc then memset the memory, one of the items in the array is not initialised to zero.  This is part of the array straight after initialisation:
......
Number of f: 0
Number of g: 0
Number of h: 134777
Number of i: 0
Number of j: 0
......

What did I do wrong?

>>23
Sepples compatibility is a red herring. Casting malloc return values is a good idea because makes intent plainer and will help catch bugs. It's just good style.

Compiling code in one language with a compiler for another language, even if it's technically possible, is always a bad idea. It's not like there's a shortage of genuine C compilers on any platform, including broken toy OSes.