Property with empty string value is not serialized? how to include NULL property also part of serrialization>

Hi Team,

Please have look at the below code

 
publicclassProductsDetail    {         publicstring Approve { get; set; }        publicstring Audit_Trail { get; set; }        publicstring Basic_Data_Text { get; set; }        publicstring Batch_Management { get; set; }    }    classProgram    {                     publicstaticString UTF8ByteArrayToString(Byte[] characters)        {            UTF8Encoding encoding = newUTF8Encoding();            String constructedString = encoding.GetString(characters);            return (constructedString);        }        publicstaticstring ConvertToIProductString(List<ProductsDetail> objIConversionFactor)        {            String XmlizedString = string.Empty;            MemoryStream memoryStream = newMemoryStream();            XmlSerializer xs = newXmlSerializer(typeof(List<ProductsDetail>));            XmlTextWriter xmlTextWriter = newXmlTextWriter(memoryStream, Encoding.UTF8);            xs.Serialize(xmlTextWriter, objIConversionFactor);            memoryStream = (MemoryStream)xmlTextWriter.BaseStream;            XmlizedString = UTF8ByteArrayToString(memoryStream.ToArray());            XmlizedString = XmlizedString.Remove(0, 39);            XmlizedString = XmlizedString.Remove(22, 99);            return XmlizedString;        }        staticvoid Main(string[] args)        {            ProductsDetail objProduct = newProductsDetail();            objProduct.Audit_Trail = "test";            objProduct.Basic_Data_Text = "testing";            objProduct.Batch_Management = "true";            List<ProductsDetail> objList = newList<ProductsDetail>();            objList.Add(objProduct);            string xmlstring = Program.ConvertToIProductString(objList);        }    }
I got the below output
 <ArrayOfProductsDetail>
<ProductsDetail>
<Audit_Trail>test</Audit_Trail> 
<Basic_Data_Text>testing</Basic_Data_Text> 
<Batch_Management>true</Batch_Management> 
</ProductsDetail>
</ArrayOfProductsDetail>
But i want the Approve element also in the list with empty value 
 <ArrayOfProductsDetail>
<ProductsDetail>
<Approve> </Approve>
<Audit_Trail>test</Audit_Trail> 
<Basic_Data_Text>testing</Basic_Data_Text> 
<Batch_Management>true</Batch_Management> 
</ProductsDetail>
</ArrayOfProductsDetail>
Please help how to do this ?