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