RCA mono? Are you talking about a digital coaxial connection? The digital out of this soundcard does not support coaxial. It has to be mini-toslink. You also have to go to the creative control center and turn on the digital output option.
In addition your TV probably doesn't support receiving a digital audio signal from your computer. For instance, if you are using DVI to HDMI, the TV expects to receive audio from the HDMI and will not offer another digital audio input for the HDMI inputs. Some TVs will have a standard RCA left/right link to the HDMI1, such as my Samsung. And if you use VGA, most TVs will only have an 8mm left/right audio.
If you actually have use for digital audio from the computer, then you'd have a receiver that supports DD or DTS and you would run the mini-toslink to toslink on the receiver and skip the TV audio.