Question the headphone not work when I plug in microphone

[sadra84]

Hi. I have A4TECH HS-28 headset. I used it for 6 months. But today without any change in using it, its microphone didn't work anymore. actually it works but not with the speakers. I mean the headphone has two jacks. one for speakers and one for microphone.
when I plug speakers jack and microphone jack together, the speakers works well, but the microphone doesn't work and just crackle. however when I unplug speakers jack and plug in my another speaker, the microphone works properly.
any ideas?
Thanks