i'm currently using the HTZ131 and it says there, u have to position the rear speakers in front and here what it says in the manual:
" Front surround 3-spot setup
This setup is ideal when rear surround speaker placement isn't possible or you want toavoid running long speaker cables in your listening area. Use this setup together with the Front Surround modes to take advantage of wall and ceiling reflections for a very realistic surround effect."
i guess you also have to turn the front speakers on...