henge dock problem

I've just got myself a henge dock for my MacBook pro late 2012 and also a bluetooth mac keyboard, only problem i have is when i close the lid the signal is lost on my external monitor. I've downloaded insomniax and clicked the correct option to disable lid sleep but it still loses the signal. I've done a ram reset but still no joy. I'm at a loss and its frustrating as want to use my dock.

any help would be very much appreciated??

cheers Rory.