Thanks for posting. I’d be happy to help with your docking station!
A quick question, are you using our Plugable brand HDMI-VGA cable --> http://plugable.com/products/hdmi-vga ? I ask because the quality of cables can vary widely, so much so we decided to offer our own HDMI-VGA version. If you are using the Plugable cable it is possible the cable is faulty, but you mention you have tried two and having two be faulty would be very unlikely (but not impossible).
A quick test to ensure your docking station is working properly would be to connect a standard HDMI cable to a HDMI monitor temporarily. This will help isolate the root cause.
Let us know the additional information and the results of testing with a standard HDMI cable if possible and we’ll go from there.