I can not use digital chaels

I can not use talkback and line imputs on my CS18AI, coected to a RM32AI. Use AVB switches you recommend and the coection is as described. I've followed all manual instructions but no links are found. I think the problem is in digital chaels. I can not assign the digital chael and make the same sound. Please help me. I am very demoralized. I absolutely needed line imputs.
Please excuse my bad English