Find my Phone includes a feature called 'Activation Lock' which is designed to prevent anyone else using the device if it's ever lost or stolen. This feature stops anyone else using the device whether its an iDevices by requiring the owner's account and password prior to activating the device, even if the device is reset. Activation Lock is enabled automatically when you turn find my phone on a device using ios 7 or later.
Please clean restore your device and jailbreak with Checkra1n 0.12.0, we are having some issues with version 0.11.