7th gen Honda Accord Parking Brake not holding

The parking brake refuses to hold even on a slight incline. I have a pretty steep driveway with a 6 speed manual transmission. If I had an automatic, I wouldn’t mind so much, but when you are cleaning snow off the car and want the car warming up at the same time or kids getting into the car before me with a parking brake that won’t hold on an incline.. that’s another story. The car doesn’t hold in gear with the parking brake on either. It starts slowly moving…

I’ve taken the car to the dealership and had a rear brake job done. Both rotors, both pads, both calipers, both parking brake cables have been replaced.

If the dealership replaced everything in the rear brake system and the parking brake cables have been adjusted, what else is there to look at? B)
The dealership is also stumped.

Is it because the tab in the new pads weren’t put into the notch of the piston as Eric has pointed out in his video? http://www.youtube.com/watch?v=3kf8C4Qxu-A at the 25 min 28 seconds? Eric points out that the would cause a spongy brake which I don’t have. …. Good Times..

Manuel