well seeing as how i wasnt overly familiar with 9.1 systems i read into it a bit more..
from what i garnered the receiver needs to support "dts neo x" or "audessy dsx" which can expand from a 5.1 or 7.1 source to your 9.1 or 11.1 speakers. on sources that are 5.1 or 7.1 it uses post processing to emulate 9 channel sound. keep in mind that this isnt quite the same as if the source was recorded in 9 channels (as that will always sound better) but its better than nothing.
you might want to read some info here http://hometheater.about.com/od/hometheateraudiobasics/qt/5-1vs7-1diff.htm
and here http://www.avsforum.com/t/1384892/is-dts-neo-x-that-good
i looked quickly at your receiver and it does state dts neo x support however what i find confusing is that it states both that dts neo x can expand a source up to 11 channels AND that it downgrades dts neo to 7.1 as well. in the manual the only thing i could find about enabling it is to set your receiver to "auto surround" or "digital" modes.
from reading a bit more into it i'd say to check your receiver modes. it could be that you have it set on a mode which doesnt activate dts neo x.
on a side note.... i'm also using a pioneer receiver (photos in signature link). they make some pretty decent hardware although my system is nowhere near the class yours is in.
if you still have issues even after trying different modes report back on what you tried.