Reply to Help - Sample Deck Setup - Turntables, A6 and 3 channel mixer

I have been searching but cannot seem to figure out how to route my sample decks into the third channel of my mixer.

I have channels C and D routed to "main out".
I have RCA's running from my "main out" into the spare channel of my mixer.

But I am not getting any sound at all.

Do I need to send sound from my booth out to the A6 and then back to the extra channel? I was believeing because the sample decks are being controlled internally that it would go straight from the A6 to the mixers extra channel.