ios sound is not playing using vuforia plugins and easy movies texture.

Hi, I have developed an app using vuforia plugin and easy movie texture. I am using vuforia video playback sample for playing video on the target image and easy movies texture for playing video from the server on the targeted image texture. It is playing fine in other device but i am getting issue in iPhone 6, iOS version is 9.3.1 sound is not playing while video is playing.please help me to resolve this issue.If any one got the same issue

Thanks.