Uran

I just got one of these boost controllers yesterday. After a few phone calls I hooked it up the the back vacume line running outa the intake manifold. Now I get only like 2psi even with the controller on max boost or min boost. I take the controller back off and just hook the hose directly back into the manifold and boost goes back up to normal. WTF is going on, ive tried hooking it up in the other direction and it makes no difference.
Anyone?