ok, in taht lies your problem..
teh only way to get front rear fade, is if you are running 4 speakers off a 4 channel amp...
not suix off 4 channels...
The 4 speakers of the front channel will see (combined) as much wattage as teh 2 in the back...
so basically, the two fronts are each seeing half of waht teh backs are...
the four speakerz connected to teh fronts are being treated as 1 set of speakers by your amp.
so, between those 4, you cannont fade between them... once you get the otehr 2 hooked up to the rear channel, you will be able to fade from the 4 speaker front stage to your 2 speaker rear stage, tahst it...