Can't Use Phone as USB Device with Keyboard Dock

[bonanzabucks]

I have a Transformer with the keyboard Dock. I have been able to use a USB stick and an external hard drive with the keyboard Dock, but it won't recognize my phone's storage, although it will charge it just fine. Is there anything I need to do to get the Transformer to recognize my phone as a USB Device? Do I need to install any software on my TF? and if so, how?

My phone is a Samsung Epic 4G on Android 2.2, if that makes any difference.

Thanks in advance.