vacuum for wash station

I cannot find resources on how to wire and plumb the wash unit and vacuum unit needed to use the wash 8 tool. When I go to wash a plate the wash 8 head dispenses but does not aspirate. I tested the vacuum at the pump. At the pump the vacuum is puling. There is no vacuum pulling at the manifold connection on the vacuum unit box though. I have the vacuum unit box plugged into rs232 on the liquid handler. There is another female plug on the box that is not connected to anything, but I cant find resources on where to connect it.

Can you please help me get my vacuum pulling through the vacuum unit box?

Thank you,

Will