error in this c# program

Question

Hi I have a program which reads a xml schema file and also reads a input xm l file and if there is a element present in the schema which is also present in imput xml fle. it stores the vaues of input xml file for theat element intoa new xml file , while the other elements present in the schema are automatically getting values acccording to the datatype. private void button2_Click(object sender, System.EventArgs e) { dataSet1.ReadXmlSchema(txtSchema.Text);//txtschema is the schema file XmlDocument xdc = new XmlDocument(); foreach (DataTable dTbl in dataSet1.Tables) { object[] oValues = new object[dTbl.Columns.Count]; xdc.Load(@"C:\CDEV\generator\testdatagenerator\FIELDNAMES.xml"); int i=0, iIndex=0; foreach (DataColumn dColmn in dTbl.Columns) { if(dColmn.ColumnName.ToString() == "billto_name") { iIndex = i; break; } i++; } //INPUT XML FILE xdc.Load(@"C:\CDEV\generator\testdatagenerator\billtoname.xml"); XmlNodeList nodeRows; XmlElement Root = xdc.DocumentElement; nodeRows = Root.SelectNodes("//billto_name"); for(int j = 0; j <= 200; j++) { int k = 0; foreach (DataColumn dColmn in dTbl.Columns) { if(j == iIndex && j