My external headset microphone will not work

I have a turtle beach 4pc headset and i'm trying to use it on my Dell Inspiron 1545. It does not have a headset port, but has both headphone and microphone jacks. I bought a converter for that. The speaker on the headset is working just fine, but i cannot get the microphone to work. I've tried enabling the Microphone / line in device and it doesn't work. someone help me get this to work please.