How can i save the fulfillmentText in dialogflow to firebase?

I am new in Learning Dialogflow, What i am trying is to save the conversation of user and the bot.

i can already save the user response to the bot but i also want to save the bot response to the firebase.

my code is like this

  function HandleSaveToDB(agent){

    return admin.database().ref('data').push({
        bot_response: request.body.queryResult.queryText,
        user_response: request.body.fulfillmentText 
    });
    
  }

the bot_response is saving but the user_response is not saving.

here is the response of the JSON

{
  "responseId": "50359194-cadb-44a4-b649-ebd8e4606fea-425db6e2",
  "queryResult": {
    "queryText": "Hi i am paul i need help",
    "parameters": {
      "given-name": "Paul",
      "text": ""
    },
    "allRequiredParamsPresent": true,
    "fulfillmentText": "Hi Paul how can i help you today?",
    "fulfillmentMessages": [
      {
        "text": {
          "text": [
            "Hi Paul how can i help you today?"
          ]
        }
      }
    ],
    "intent": {
      "name": "projects/chatsimulator-rttunh/agent/intents/dbc7dbf8-ca8d-4f7a-86b5-a0e6eab7e0b5",
      "displayName": "Greetings"
    },
    "intentDetectionConfidence": 1,
    "diagnosticInfo": {
      "webhook_latency_ms": 4992
    },
    "languageCode": "en"
  },
  "webhookStatus": {
    "code": 4,
    "message": "Webhook call failed. Error: DEADLINE_EXCEEDED."
  }
}