Git Alias Problem

Question

I was trying to set up some git aliases by adding these lines to my ~/.gitconfig file:

[alias]
  st = status
  ci = commit
  br = branch

And when I go to run these commands in the terminal: git st, I get the following error fatal: cannot exec 'git-st': Not a directory. I do not know what the problem is and I have looked online and cannot find why it is doing this. I am running Mac OS 10.6.4 using Git 1.7.1. Somebody please help me out. If I don't figure out why it is doing this, I'll go crazy! Thanks!