Hi Bill As Thomas M above points out, make sure your soffits are not blocked, to include having insulation up against the back of the roof deck. This must all be kept clear so that air can rise up into the attic space and the warmest air leave through the ridge vent. It is vital that this be a passive ventillation system. I strongly advise that you not use any kind of power vent system...first because they dont vent well at all and second, what they do vent is forced, which creates a lower air pressure in the attic, which will have a tendency to draw air up from your living spaces below. Also, be sure that the ridge vent is kept clear of snow. A blocked ridge vent will effectively stop attic ventillation.