More than 2 displays on HP 8570p Laptop

Hi,

I have a 8570p laptop with the AMD Radeon HD 7570M discrete graphis card and a HP docking station

I'm unable to have 2 external monitors + the laptop monitor wokring at the same time.

I've tried using the following configuraitons for the external monitors on the docking stations:

Displayport + DVI

Displayport + VGA

DVI + VGA

Any ideas on how I can solve this?

Thanks!