dr dre microphone not working properly with Iphone 4?

Hello I have recently got Iphone4, when I listen to the music on my Dr
dre studio headphones on it, it works fine but, when I try call some
one using the headphones(cable with microphone), the people say they
cant hear me properly???

is there any 1 here can help me solve my problem.

I have tried using the headphones on other phones it is working
properly.

Pls help me fast