wx.onBLECharacteristicValueChange无法执行回调？

wx.notifyBLECharacteristicValueChange({
              deviceId,
              serviceId,
              characteristicId: item.uuid,
              state: true,
              type: 'notification',
              success(res) {
                console.log("参数"+deviceId+'---'+serviceId+'---'+item.uuid)
                console.log('notification通知数据', res)
            },
            fail(res) {
                console.log('notifyBLECharacteristicValueChange fali', res);
            }

            })

执行完这个notify之后 参数都没问题 并且返回ok 但是无法进入wx.onBLECharacteristicValueChange()方法 就没办法拿到最新的特征值 这是什么问题呢