Not all functions in all applications are supported. The Volume and Answer/End buttons were designed specifically to work with iPhone® and core Apple® applications. Third-party applications and non-Apple products may have no or limited functionality. If you are experiencing inconsistent functionality with the Answer/End and Volume buttons, we suggest you try the following:
Control button troubleshooting
Answer/End and Volume buttons do not work or work intermittently.
Remove and reseat the input cable from the phone. The input cable may have come loose or may not be inserted properly. Remove the cable from the phone and reseat it
Be sure the answer/end button is pressed in the center and not off axis
Be sure the button is not stuck in the down position. When pressed, the button should depress then snap back into its original position. Pressing the button a few times should verify if it is stuck
Make sure “shake-to-shuffle” mode is turned OFF on your iPod or iPhone. This feature, available in newer models, lets you change the track that’s playing just by shaking the unit. If it’s not turned off, the feature could be activated inadvertently—for instance, by the movement of placing your iPod in your pocket. Turn the feature off, then check the answer/end button again