MR816csx routing.

I need some help here guys, I’m getting to the end of my rope. I’m using pro tools 10 with a steinberg mr816csx and a RNC. I’m having problems with the routing. I thought it was a problem with my patchbay, but i tried it today with no patchbay and I’m getting the same results. I’m routing the compressor as an insert on my master bus and I can hear compression and see the compressor working, but if i try any type of make up gain i get crazy amounts of feedback. The feedback also gets worse when I increase the master volume to my monitors. I just don’t get it.
My routing is
Insert 7-8 in Pro tools -> MR line outs 7-8 -> RNC inputs 1-2 -> RNC outputs 1-2 -> MR XLR/Line combo inputs 7-8

Am I doing something wrong to get all this feedback? Any help would be awesome.

Anybody else experiencing this? I can’t be the only one trying to use outboard gear with this unit.