If you have more than one physical screen but only the one screen is activating there a number of things that you can try:

Right click on an empty spot on your desktop and select "Screen Resolution:

In the screen that pops up click on the pop down menu under the "multiple displays" heading and select "Extend these displays".

Now press the apply button.

Your screen will go black for a few seconds and then your second screen should come up. Select "Keep Changes" to have the new settings stick.

If there is no option for a second display: Check the cables going into your computer (or docking station) and the cables going into the screen.  press the power button on and off on the screen and try rebooting your computer.  If you are still unable to get your second monitor working please submit a ticket.