Create an XML Document on the fly

I want to produce this:

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE CreateLoanPrincipalPayment SYSTEM "CreateLoanPrincipalPayment.dtd">

<CreateLoanPrincipalPayment

loanAlias="CHG8F47RP"

effectiveDate="10/07/2005"

requestedAmount="1000000"

version="1.0">

</CreateLoanPrincipalPayment>

C# Code:

using Services.LoanIq;

        private string GetXml(string functionName)

        {

            try

            {

                XDocument xdoc = new XDocument();

                XDocumentType documentType = new XDocumentType("CreateLoanPrincipalPayment",

                                                 null,

                                                 "CreateLoanPrincipalPayment.dtd",

                                                 null);

                xdoc.AddFirst(documentType);

                xdoc.Declaration = new XDeclaration("1.0",

                                       "utf-8",

                                       null); // Note: this will get dropped off automatically

                xdoc.Add(new XElement("CreateLoanPrincipalPayment",

                             new XAttribute("version", "1.0"),

                             new XAttribute("requestedAmount", "1000000"),

                             new XAttribute("effectiveDate", "10/07/2005"),

                             new XAttribute("loanAlias", "CHG8F47RP")));

                //So you have to add it back here

                string returnValue=xdoc.Declaration + Environment.NewLine + xdoc;

               

                return returnValue;

            }

            catch (Exception ex)

            {

               

                throw;

            }

        }