(UNO card game) I can't get the data with GetComponent function for an instance of an object

Hi! This is kind of hard to explain but I'll do my best.

I'm making a UNO card like game, at starting the game it spawns a random card, with a random number an color and then you have to place a matching card there, but when trying to store the data for the number of that initial card in another variable, it doesn't detect it.

I have two functions:

1. InitialCard() spawns the first card and try to obtain it's data (doesn't obtain it)

2. DropCard() is when the player drags a card and dop it above the first or previous one and it works, the Debug shows the number of that card

   ---

So if in the DropCard() works, why doesn't work in InitialCard() that is exactly the same and should work? Please help.

(the code below is sumarized, I only show the relevant part, I erased some things but doesn't affect the situation)

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 
 public class PlaceArea : MonoBehaviour{
 
     [HideInInspector]
     public int placedNumber;
 
     //Cards
     [HideInInspector]
     public GameObject currentCard = null;
     [HideInInspector]
     public GameObject newCard = null;
 
 
     void Start()
     {
         InitialCard();
     }
 
     //Here is where the first card appears with his own random number and try to obtain his number data in the variable "placedNumber"
    
  void InitialCard()
     {
         //initial card instance and position
         currentCard = Instantiate(manager.initialCard, new Vector3(0, 0, 0), Quaternion.identity);
         currentCard.transform.SetParent(gameObject.transform, false);
 
         //initial card data (*ERROR HERE*)
         placedNumber = currentCard.GetComponentInChildren<CardsData>().cardNumber;
         Debug.Log("card data: " + placedNumber);
     }
 
     //Here is where it tries to obtain the data for all the new cards that are dropped above the first card ^^ and it does works perfectly, it can get the number data of that card in "placedNumber" but in the first one it can't
    
  public void DropCard()
     {
         //new card data (works fine)
         placedNumber = newCard.GetComponentInChildren<CardsData>().cardNumber;
         cardIsPlaced = true;
         Debug.Log("card data: " + placedNumber);
 
         Replace(currentCard, newCard);
         image.color = normalColor;
     }
 }

This is what happens graphically: If something isn't clear please tell me and I would nicely clarify anything. Is there anyone else trying to make a UNO like game or any card game?