翩翩起舞--写入特性错误

我无法在出血性设备上写入，使用 flutter_blue 库，它抛出了这个异常。

Unhandled Exception: PlatformException(write_characteristic_error, service (0000ff06-0000-1000-8000-00805f9b34fb) could not be located on the device, null, null)
E/flutter (29808): #0      StandardMethodCodec.decodeEnvelope (package:flutter/src/services/message_codecs.dart:607:7)
E/flutter (29808): #1      MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:167:18)
E/flutter (29808): <asynchronous suspension>
E/flutter (29808): #2      BluetoothCharacteristic.write (package:flutter_blue/src/bluetooth_characteristic.dart:120:18)
E/flutter (29808): <asynchronous suspension>
E/flutter (29808): #3      DeviceScreen._buildServiceTiles.<anonymous closure>.<anonymous closure>.<anonymous closure> (package:untitled/main.dart:176:23)
或者另一个错误说：Write is not permited。
我正在使用flutter blue库提供的示例代码，以下是我在设备连接后试图写入的代码。
onWritePressed: () async {
                      await c.write(_getRandomBytes(), withoutResponse: true);
                      await c.read();
                    onNotificationPressed: () async {
                      await c.setNotifyValue(!c.isNotifying);
                      if (c.properties.read) {
                        await c.read();
List<int> _getRandomBytes(){