- Inspect the dock connector on the iPod for bent or missing contacts, foreign material, corroded contacts, broken, missing or cracked plastic.
Sometmes this works
- Reset the iOS device. Nothing will be lost
Reset iOS device: Hold down the On/Off button and the Home button at the same time for at
least ten seconds, until the Apple logo appears.
- Reset all settings
Go to Settings > General > Reset and tap Reset All Settings.
All your preferences and settings are reset. Information (such as contacts and calendars) and media (such as songs and videos) aren’t affected.
- Restore from backup. See:
- Restore to factory settings/new iOS device.
Otherwise go to the dock manufacture's support site. Sometimes an iOS update breaks compatibility and you will have to wait for either an iOS update (very unlikely) or an update to the firmware on the dock