HELP!! Reefkeeper RO system no Output

[ocellaris_keeper]

I just put togeth a 75GPD reefkeeper RO/DI system and I am not getting any water from the unit.
I installed it exaclty as the instructions indicated. What could be wrong.
Connected the IN line to the cold water - watched the water fill up the first stage.
Removed the connection for the third filter (right before teh 4 way junction - water is running. Checked after the junction - Nothing!!
What's the deal?
Please Help

 

[mlm]

You may not have enough water pressure. Where does your water come from. A well or is it city water? If it is city water do they use a water tower to build pressure?

 

[ocellaris_keeper]

How much pressure do I need? It seems I have lots of pressure in the house including wehere I connected the unit.
Even if I had none wouldn't it do something?