Unable to use 2 external HP P221 Monitors along with internal display of HP laptop EliteBook 8570p

I am using:-

 1.Two external monitors - both monitors are HP ProDisplay P221. Both of these are being connected via DVI cable.

 2.Laptop is "HP EliteBook 8570p"

 3. HP advanced docking station "A7E36AA"

I want to use the internal display of laptop along with 2 external monitors. When I try to 'apply' for the 2nd external monitor it says "Unable to save display settings"

It is fine in the below configurations:-

  1. Laptop + 1 external monitor

  2. Two external monitors (without the internal display of laptop)

Error comes up only in the combination of LAPTOP + External Monitor(HP P221 via DVI) + External Monitor (HP P221 via DVI).

Please advice.

Many thanks,

-krish