Can't load Codeigniter drivers, bug or am I going insane?

[eluser]Vheissu[/eluser]
I've been developing a driver based payment library for Codeigniter and have noticed my sub drivers are not being loaded even though I am following the proper naming conventions. Can anyone see any issues with how I've code the drivers thus far? https://github.com/Vheissu/CI-Payments

The error I am getting is: "An Error Was Encountered Invalid driver requested: Payments_paypal"

I've looked at countless driver examples and this should be working. I can call functions within the main Payments library, but not sub drivers. You can see in my code I am setting a default driver and then loading a function from within it, so something is going wrong when trying to access child classes (drivers).