Audio Line In Port

Hello,

I'm a Final Cut Pro savy user who's trying to see if she can digitize audio in from my smartphone (Palm Pre). However, my computer isn't recognizing the audio input when I'm connected via a stereo mini cable from my phone's headphone jack to the line in port. I've gone into system prefs / input and made sure the "line in" device is selected. I also know the cable is transmitting audio since my husband checked it on another device. Any advice? Is this even possible?

Thanks.