I need help on a program I am currently creating as all I am trying to do is read all the cells in the datagrid to see if there are any null values and then display a message. I have racked my head around this for ages and I just cant find any code to help. Below is the code I am trying to use to search through each cell but this throws an exception that datatable cannot be converted to dataset. Any help would be appreciated.

Code:
 string CellVal = null;
            int Rowcount = 0;
            CurrencyManager cm = (CurrencyManager)this.BindingContext[this.dataGrid1.DataSource];
            int rowCount = cm.Count;
            int colCount = ((DataTable)this.dataGrid1.DataSource).Columns.Count; 
            for (int row = 0; row < rowCount; row++)
            {
                for (int col = 0; col < colCount; col++)
                {
                     CellVal = this.dataGrid1[row, col].ToString();
                }
            }