Problem interfacing Bluetooth dongle with Arduino Mega ADK

Hello, I am trying to send messages to the Arduino Mega ADK( from an Android phone) via Bluetooth by connecting a Bluetooth dongle directly to the USB port of the Arduino Mega ADK. I was able to directly connect the phone to the ADK and control an LED using the demokit app on the android phone and an appropriate code on the Arduino( Demokit.pde). However when i tried to connect a USB dongle, When I check whether the accessory is connected or not ( using acc.isConnected()), I am getting the following error "Device addressed... Requesting device descriptor. found possible device. swithcing to serial mode Data packet error: 4could not read device protocol version"

Does this mean that I do not have the correct libraries installed for the Bluetooth dongle? If not can anybody please suggest me what to include(any compatible drivers)? And could you please help me out on how to proceed ? Thank You