The laptop screen goes dark when plugged into the docking.

Do you turn the laptop off before docking it?  If not try shutting it down, dock it, then turn on using the docking power button.

I agree with the above.

If that does not work, update the BIOS, Chipset, Power Manager and Power Driver.  Do this via the PC manufacturer's driver update application.

Is your dock connected to 1 or 2 monitors?

Before doing anything major like updating your bios, try locating the screen toggle function key.  I don't have a keyboard in front of  me at the moment, but it's usually near the F7 key and has a rectangular icon.  Each press will toggle video between the laptop screen, external port or both.

Is the laptop configured to send its display output to an external monitor when it detects that it's been connected to the docking station? If so, it won't necessarily check that there is a valid display connected to the docking station - it's more likely to assume that one is present and therefore disables the laptop screen.

Make sure you are using the power supply that came with the docking station and not the powersupply that came with the laptop.  The powersupply that came with the laptop does not provide the amps required to power both the laptop and docking station.