notify使能,发生not mapped的错误

我使能notify的代码如下所示  

bStatus_t send_custom2_notify_enable(uint16 connHandle,uint8 taskId )
{
  bStatus_t req_res = SUCCESS;
  attWriteReq_t req;
  
  req.handle = SNM_CUSTOM2_NOTIFY_HANDLE;//18
  req.len = 2;  //data length
  req.pValue[0] = LO_UINT16(PRF_CLI_START_NTF);//0x0001
  req.pValue[1] = HI_UINT16(PRF_CLI_START_NTF);
  req.sig = 0;  //not included
  req.cmd = 0;
  
  req_res = GATT_WriteCharValue(connHandle,&req,taskId);
  return req_res;
}

抓包工具抓到信息如下,显示not Mapped,请问这个是怎么造成的?

下面这个是我用手机app连接抓的包,我想正常应该是这种