Cant reach the datagridview1 control

Question

Hi,
Im facing a weird problem. I am just adding a DataGridView control to my program's interface. Then I am passing the Form1.cs then wanna write some codes with this control but VS can not see this control.  I mean can not identify. All codes below ;
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 private void button1_Click(object sender, EventArgs e)
        {
            string query = "Data Source=1.1.1.1;Initial Catalog=mdb;User Id=user;Password=qweasd;";
            SqlConnection conn = new SqlConnection(query);
            conn.Open();

            DataTable data_table = new DataTable();

            SqlDataAdapter sql_adapter = new SqlDataAdapter("SELECT * FROM table", conn);
            sql_adapter.Fill(data_table);

            datagridview1.Fill ......    --> I cant fill dataadapter to gridview..
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