[Code Igniter] Unable to locate the specified class: Session.php [SOLVED]

I'm using the Code Igniter, and when executing a controller the page throws "Unable to locate the specified class: Session.php" error.

After much debugging, I found that if you are using identical library name on the controller you may be getting this error.
In my case, I was loading a library called "Sales" in the "Sales" controller. After renaming the controller to "Reports", the problem was solved.