Non-invocable member 'form1.datagridview1' cannot be used like a method

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C#

Visual-Studio

Attention to all, I need your help I'm using c#. The error message said, the datagridview1 cannot be used like a method. Please help me to fix this issue.

here's my code.

private void ShowSchedule()//show color
        {
            string ConString = "server=localhost;user=root;database=carrental;password=;";
            MySqlConnection Con = new MySqlConnection(ConString);
            Con.Open();

            string query = "Select * from rent_schedule Where startBook >= @ST AND endBook <=@ET";

            DateTime startDate = new DateTime(monthCalendar1.SelectionStart.Year, monthCalendar1.SelectionStart.Month, 1);
            DateTime EndDate = startDate.AddMonths(1);

            MySqlCommand cmd = new MySqlCommand(query, Con);

            cmd.Parameters.AddWithValue("@ST", startDate);
            cmd.Parameters.AddWithValue("@ET", EndDate);

            MySqlDataReader dr = cmd.ExecuteReader();

            while (dr.Read())
            {
                int id = dr.GetInt32(0);
                DateTime startBook = dr.GetDateTime(2);
                DateTime endBook = dr.GetDateTime(3);

                int startBook_C = startBook.Day;
                int endBook_C = endBook.Day;

                int TotalDays = endBook_C - startBook_C;

                dataGridView1(startBook_C, id - 1).Style.BackColor = Color.Blue;
                //dataGridView1.Rows[2].Cells[0].Style.BackColor = Color.Blue;

                int i;
                for (i = 1; i <= TotalDays; i++)
                {
                    dataGridView1(startBook_C + i, id - 1).Style.BackColor = Color.Red;/* TODO ERROR: Skipped SkippedTokensTrivia */
                    TotalDays -= 1;
                }


            }
            Con.Close();
        }

What I have tried:

now my expecting output like this, Please click the link image below.

https://i.sstatic.net/3Xvqg9lD.png[^]

My problem is I do not know how to fix my datagridview error. Thank you so much who can help me or fix my problem.