else{

      console.log(app.globalData.characteristicId11)

      console.log(app.globalData.deviceId1)

      console.log( app.globalData.serviceId1)

           wx.notifyBLECharacteristicValueChange({

            state: true,

            characteristicId: app.globalData.characteristicId11,

            deviceId: app.globalData.deviceId1,

            serviceId:  app.globalData.serviceId1,

        success (res) {

          console.log("notifyBle success")

          wx.onBLECharacteristicValueChange(app.RX_Service1)

      },

      fail(res){

        console.log('notifyBLE执行失败',res)

      }

    })   

 //发送数据

    let brandandlook=[0x9e,0x09,0x01,0x82]

    app.TX_Service1(brandandlook)  

    if( app.globalData.carandmode_set_point){

    app.globalData.carandmode_set_point.setData({

        blue_status_ready666: true

    }) 

    }

    wx.navigateBack({

      delta: 0,

    })

    return

    }

 请问wx.notifyBLECharacteristicValueChange（）执行，但是 wx.onBLECharacteristicValueChange(app.RX_Service1)不执行，是什么原因