Pro Tools 11 - Inputs not showing in channels

Hello,



I am using Pro Tools 11 Native on a PC running Windows 7 Professional 64 bit. I have two Aurora 16's synced using two RME HDSP cards.



I have set up 16 mono inputs of my 16 preamps in the I/O section. Everything is correctly assigned in the matrix.



Unfortunately, only 8 of the preamps show up as input options in my mono channels. Can anybody suggest a possible reason for this?



Thanks to anybody who replies.:-)



Frank