Object reference not set as instance of an object (2.0) [duplicate]

I am getting an error called "System.NullReferenceException:" in my C # program.

I have searched on this website how to solve it and I have read that it is usually because the initialization is not used, so the values that it tries to access are "null".

However, I'm reviewing and I see that I initialize these values using the "new" (or at least I think I do).

This is the problematic fragment of the code:

 public bool load(string fileName)
    {
        // Read the board from "fileName" and fill the _cells with its information
        try
        {
            using (StreamReader sr = new StreamReader(fileName))
            {
                int validLines = 0;
                int currentRow = 0;
                string line = sr.ReadLine();

                while (line != null)
                {
                    if (validLines == 0)
                    {
                        int.TryParse(line, out _numRows);
                        validLines++;
                    }
                    else if (validLines == 1)
                    {
                        int.TryParse(line, out _numCols);
                        validLines++;

                        _cells = new Cell[_numRows, _numCols]; /*INICIALIZO LA ARRAY CELL*/
                    }

                    else
                    {
                        int currentCol = 0, j = 0;
                        for (int i = 0; i < _numCols; i++)
                        {
                            j++;

                            if ((line[j] > 0 && line [j] < 9) || line [j] == 'B' || line[j] == 'V')
                            {
                                _cells[currentRow, currentCol] = new Cell(CellState.Covered, line[j]); /*INICIALIZO CADA INSTANCIA DE LA ARRAY CELL*/
                                currentCol++;
                            }
                            else
                            {
                                i--;
                            }
                        }
                        currentRow++;
                    }
                }


                while ((line = sr.ReadLine()) != null)
                {
                    Console.WriteLine(line);
                }
            }
        }
        catch (Exception e)
        {
            Console.WriteLine("The file could not be read");
            Console.WriteLine(e.Message);
            return false;
        }
        return true;


    }


    public void print()
    {
        // Print the content of the board

        for (int i = 0; i < _numRows; i++)

            for (int k = 0; k < _numCols; k++)
            {
                Console.Write(" " + _cells[i, k].getContent()); 
                //AQUÍ ES DONDE ME NOTIFICA QUE SUCEDE EL ERROR


            }
        }
        Console.ReadKey();
    }

Can someone locate where the error lies? I understand that for some reason the values in the array _cells [] remain as null, so when I apply the print () method the program peta and returns error.

Thank you.