Update to the latest version of iOS
Some accessories might require the latest version of iOS. Make sure that you update to the latest version of iOS.
Make sure the accessory is compatible
If this is the first time that you tried to use the accessory, make sure that it works with your device. Some accessories only work with certain models of iPhone, iPad, or iPod touch. If you aren’t sure, contact the manufacturer.
Check the connections
Disconnect and reconnect the accessory to clear the alert. If the alert continues to appear, check the connectors on the accessory and your device for damage or debris. If necessary, gently remove the debris and clean the connectors on your device.