I'm using dataGridView in Windows Forms to show the database and want to color it. If [Solver] column is NULL it should paint LightSalmon, else LightGreen. However even if the column value is NULL it still see it as not null and paint into LightGreen.

```
This is my table:
      [Id]
      [Employee]
      [Section]
      [Machine]
      [Station]
      [MachNo]
      [Area]
      [Type]
      [Desc]
      [Recommendation]
      [Date]
      [Solver]
      [Process]

public void Color()
{
    for(int i = 0; i< dataGridView1.Rows.Count; i++)
        if (DBNull.Value.Equals(dataGridView1.Rows[11]))
        {
            dataGridView1.Rows[i].DefaultCellStyle.BackColor = Color.LightSalmon;
        }
        else
        {
            dataGridView1.Rows[i].DefaultCellStyle.BackColor = Color.LightGreen;
        }   
}

```