Need help... 2007 Yaris with Aux plugin

[molinee]

I tried to do my DD on this and checked out nearly all the topics with no luck. I have a 2007 Yaris hatchback. It has an AUX plugin between the seats. I can plug in my MP3 player and the stereo will play the music. I am now trying to put music on a flash drive and play the flash drive thru the Aux plugin. I am using a special connector that has a USB plug on one end of the cable and what appears to be a 3.5 plugin on the other. I connect the USB flash drive to the one end of the cable and plug the other end of the cable into the AUX and then push AUX on the radio. What shows up on the radio is the word AUX but nothing else and obviously there is no music. All of my files are MP3 so I am assuming that they should play. Anyone have any ideas as to what is going on? This special connector that I bought made it sound like it would work but either this is wrong or I am missing something...

Any help appreciated my Yaris friends...