I had a similar problem with my head unit. Did you go onto the unit and turn on the aux input? Not entirely familliar with clarion's stuff so maybe this has no relevance but on the pioneer I've got, you actually have to open up a menu on the unit its self and switch aux input to on.
Hope it helps.
"I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones." - Albert Einstein