Gave up on listening music on my E398

I was a bit thrilled yesterday when I found several kinds of cables in a electronic store at the ground floor of Golden that converts a tri-channel 2.5mm plug into a 3.5mm stereo headphone plug. And I thought, awesome, now I could now use my headphone with my Motorola E398, which is a mobile phone with tr-channel on the audio jack. But then I used my mobile, and found that NONE Of them really work on my phone.... how sad.. why... why ...