Ford Fiesta aux sound muted

This is from the owners handbook , 1. Make sure your vehicle is stationary with the radio and portable music players turned off. 2. Plug the extension cable from the portable music player into the auxiliary input jack. 3. Switch the radio on. Select either a tuned FM station or a CD. 4. Adjust the volume as desired. 5. Switch the portable music player on and adjust its volume to half its maximum level. 6. Press AUX until LINE or LINE IN appears in the display. You should hear music from your device even if it is low. 7. Adjust the volume on your portable music player until it reaches the volume level of the FM station or CD. Do this by switching back and forth between the AUX and FM or CD controls.