5.1 Export is always playing Center channels on the left.

Hi, I'm having a nightmare trying to export 5.1 audio from Premiere. I have tried everything I can find online about how to export correctly and nothing is working.

I have a ready mixed 5.1 track which I have been able to import as 6 seperate mono tracks. I have panned them all correctly and when I export I always select 5.1 (L,R,C,LFE,SL,SR). My dialogue track is track 3 which is properly mapped and should export as the center speaker. However, whenever I export it swaps the dialogue with track 2 so it comes out of the left speaker. The only time it seems to work is when I select to export (L,R,SL,SR,C,LFE). My worry is that this isn't actually the correct order in the 5.1 mix I have and that when it is opened on another machine (in DCP format in a theater) the mapping will be completely off. I don't really have a way of checking this. 

Does anyone have the faintest idea on why adobe isn't exporting the tracks to the correct channel?