Boost Leak Test Woes

I am trying to preform the boost leak test that is described in the FAQ section but I have a problem. I have a pancake compressor with a regulator turned down to 20 PSI and Im using an air nozzle with a vacuum line attached to it. Right now I have the vacuum line attached to the return plenum, connected to the vacuum nipple that has a line that goes to the inlet plenum. I believe its called the crossover. Well, when I attempt to pressurize the system it sounds like all the air is going out through the exhaust manifolds. Since I have one of the crossover vacuum lines unhooked for the leak test i figured air would be leaking out the other nipple on the inlet plenum but its not. What is going on? I also don't hear a hissing at the TB it just sounds like all the air is going out through the exhaust. I did a compression check and all the numbers came back alright so Im a little confused.
As Usual, thanks for all the input,
Phil

It's much easier to just spray all the vacuum and PCV related hoses and IC tube connections with carb cleaner while the engine is running. If there is a leak you'll find it in less than a minute.

David