I recently installed a free-way switch into my strat which has a SD STK-S2 hot stack pickup in the neck, original Fender p/u (1966) in the middle and Dimarzio in the bridge. Everything appears to be wired up and functional, but I have noticed that when the neck SD pickup is in series with either of the other two the volume seems to be less rather then greater. This is almost like the neck is out of phase with the others, but I have the green wire at ground per the instruictions. By any chance is this a known issue due to the pickup resistance, winding, etc. being different from the others? Thanks for any help.