title: BluetoothGatt.writeCharacteristic() always returns false.
body: <p>I am writing an Android app to talk with an Arduino using BLE.  I have been able to scan devices, connect to the target, discover services, get characteristics, and read those that are readable.  However, when I try to write a writeable characteristics, the method always returns false.  When I debugged into the android.bluetooth code, the following sequence occurs: 
  characteristic.getService().getDevice always returns null, 
  which causes the writeCharacteristic to fail.  </p>
  
  <p>Any help is greatly appreciated!</p>