Note: It needs the Bluetooth to transfer the audio when you use android phone's mirrorlink. Please connect car stereo's Bluetooth first! 1. Try another usb cable. (Original usb cable or good quality usb cable needed, it needs the usb cord to transfer data, so the quality is very important) 2. If it is mirrorlink for an Android phone, please check whether you have downloaded the mobile app that supports this function before using the mirroring function. 3. Restart your phone and replug the usb cable. 4. Reset the unit with the reset hole.