EGR Valve trouble

My check engine light have been coming on now for a few months. The code is 12, for the EGR Valve. Removing the vacuum hose from the valve, i find that there is no vacuum in the line. I traced it back to the control box, and the solenoid for the control of the vacuum to the egr valve. I replaced this but it still does not work, still no vacuum. I'm running out of idea on this, can somebody please help, i don't know what else to look for or replace? Thanks.