First, turn your device's Bluetooth setting to "On." This is indicated with the Bluetooth symbol next to the battery symbol in the upper right-hand corner. When the Bluetooth symbol is grey, it means that there are no devices paired. When the Bluetooth symbol turns white, it means that it is connected to a device.
To connect your power meter to the PowerTap Mobile app, make sure that no other devices are paired to your iOS device. We recommend killing any applications that may connect to the Bluetooth sensor.