Different type of errors in ASP.Net

Object must implement IConvertible


Error Code:
StringBuilder itemNumbers = new StringBuilder();
DataView DV = DS.Tables["Products"].DefaultView;
int DVRowCount = DV.Table.Rows.Count;
if (DVRowCount > 0)
{
foreach (DataRow dr in DV.Table.Rows)
{
sItemNumbers.Append(Convert.ToString(dr["Prod_Id"]));
sItemNumbers.Append(",");
}

ArrayList oArrParam = new ArrayList();
oArrParam.Add(new Parameter("@itemNumbers", itemNumbers, ParamDirection.Input, DbType.String));
}

The problem: you need to convert string builder value to string. The code should look like this:

ArrayList oArrParam = new ArrayList();
oArrParam.Add(new Parameter("@itemNumbers", itemNumbers.ToString(), ParamDirection.Input, DbType.String));}