i have an 4s with this problem... BUT i have no idea of who the preveus owner is.... anything to do?
Resolution
If the device has already been erased
If the device has already been erased, but is still linked to the previous owner’s account, you will be prompted for the previous owner’s Apple ID and password during the device setup and activation process (shown below).
If the previous owner is with you and can access the device
Ask them to enter their Apple ID and password on the Activate iPhone screen (shown above) to remove the device from their account. You can then proceed through the rest of the device setup process.
If the previous owner is not present
Contact them and ask them to follow these steps to remove the device from their account:
Sign in to their iCloud account at
www.icloud.com/find.
Choose the device from their Find My iPhone device list by clicking All Devices and selecting the correct device.
Click "Remove from Account" to remove the device from the account.
After the device has been removed from the previous owner’s account, turn it off by pressing and holding the Sleep/Wake button located on the top right side of the device. Then restart your device and proceed with device setup as you would normally.