C# - DatagridView with Checkbox column cell click

• Pls everyone help me.... if i click the datagridview checkbox columns 1 to 4 rows, but 1,2,3 rows only false 4th row wasn't false...??? for eg: 1 to 5 rows means 5th rows wasn't false.... why..?? If you provide more details we can provide better help.... Coding and project file have been mentioned below.......

            int i=0;
    foreach (DataGridViewRow item in dataGridView14.Rows)
    {
        if (item.Cells[0].Value != null)
  
            if (bool.Parse(item.Cells[0].Value.ToString()))
            {
                item.Cells[0].Value = false;
                MessageBox.Show("Selected Rows : " + item.Cells[0].RowIndex.ToString() + "  and serial No is" + item.Cells[1].Value.ToString());
            } }