Oppo CD/ Channel Islands DAC connectivity issue

I recently got a CIA VDA-2 DAC.  I connected my iMac to stream music from my external HD to the DAC via a Toslink cable and from it to my preamp via RCA interconnects and it works dandy.  However, the DAC only as two inputs: a Toslink and a digital input (RCA) .  I connect my Oppo CD player from the coax jack on the back of it to the digital input on the DAC via a Belden 1694A digital cable, which is terminated on both ends with RCA connectors.  With this connection to my DAC, I get no signal to the DAC.   Can somebody give me an idea of what I am doing wrong?  It has been suggested that I need to re-program the output of the Oppo, but I have no idea what that entails.  
Thanks for any advice you sharp fellows can provide. Cheers, Whitestix