LePIC

Hi, I bought 2 x Steinberg UR824 to have 16 microphones inputs. I work with Logic Pro X 10.6 on a MacMini (Catalina). 1 - I connected my first UR824 to set up the clock and set it to ADAT B In into the Audio/MIDI configuration of my MacMini. 2 - In the DSPMixFR_USR824, in the parameters I assigned the inputs from 9 to 16 ADAT OUT B. 3 - I then turned off the power, and connected my 2nd UR824 which I set the clock to Internal to make it my master. 4 - I connected 2 optical cables in the ADAT B Out of the slave to the ADAT B IN of the master, and the ADAT B In of the slave to the ADAT B out of the master. In Logic Pro, my inputs 1-8 work, but not 9 to 16, can you tell me what I have forgotten?