Eye 4 gives no sound in windows

I have jsut installed Eye 4 in my PC and connected the 2 IP camera at my home successfully , I can see the image without any problem but I cannot hear any sound from the camera even I am sure that the speaker of my PC is on and I have clicked the "headphone" button in the control panel of Eye 4 to switch it on already. May I ask what can I do to get the sound back? The camera works perfectly when I am using my iPhone (image and sound can be obtained).

Thanks  for your support VStarcam .
Do the camera like this picture.
but, you can use the smartphone  application have a try .  
my Email is: support@vstarcam.com

Make sure the camera is turned on from the very beginning and that all connections are secure.