Asymmetric Decryption Problem

Hi,

I have written some code that has encrypted an XML config file containing user credentials, and also the code to decrypt that file. When I run the encryption and decryption together on my local machine it works as expected. However, when I deploy the program, with only the decrypt code, the xml file will not decrypt. I get a cryptographic Exception: Bad Data?
Here is my code:

Code:

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public static void Encrypt(XmlDocument Doc, string ElementToEncrypt, string EncryptionElementID, RSA Alg, string Keyname)
        {
            if (Doc == null)
                throw new ArgumentNullException("Doc");
            if (ElementToEncrypt == null)
                throw new ArgumentNullException("Element to Encrypt");
            if (EncryptionElementID == null)
                throw new ArgumentNullException("EncryptionElementID");
            if (Alg == null)
                throw new ArgumentNullException("ALG");
            //specify which xml elements to encrypt
            XmlElement elementToEncrypt = Doc.GetElementsByTagName(ElementToEncrypt)[0] as XmlElement;

            if (elementToEncrypt == null)
                throw new XmlException("The specified element was not found");
            try
            {
                //create session key
                RijndaelManaged sessionkey = new RijndaelManaged();
                sessionkey.KeySize = 256;

                //encrypt using Encrypted exml object and hold in byte array
                EncryptedXml exml = new EncryptedXml();
                byte[] encryptedElement = exml.EncryptData(elementToEncrypt, sessionkey, false);

                //Construct an EncryptedData object and populate
                // it with the desired encryption information.

                EncryptedData edElement = new EncryptedData();
                edElement.Type = EncryptedXml.XmlEncElementUrl;
                edElement.Id = EncryptionElementID;

                edElement.EncryptionMethod = new EncryptionMethod(EncryptedXml.XmlEncAES256Url);
                //encrypt the session key and add it encrypted key element
                EncryptedKey ek = new EncryptedKey();

                byte[] encryptedKey = EncryptedXml.EncryptKey(sessionkey.Key, Alg, false);

                ek.CipherData = new CipherData(encryptedKey);
                ek.EncryptionMethod = new EncryptionMethod(EncryptedXml.XmlEncRSA15Url);


                // Create a new DataReference element
                // for the KeyInfo element.  This optional
                // element specifies which EncryptedData
                // uses this key.  An XML document can have
                // multiple EncryptedData elements that use
                // different keys.
                DataReference dRef = new DataReference();

                // Specify the EncryptedData URI.
                dRef.Uri = "#" + EncryptionElementID;


              //add data reference to encrypted key

                ek.AddReference(dRef);
                //Add the encrypted key to the
                // EncryptedData object.

                edElement.KeyInfo.AddClause(new KeyInfoEncryptedKey(ek));

            // Create a new KeyInfoName element.
            KeyInfoName kin = new KeyInfoName();

         

            // Add the KeyInfoName element to the
            // EncryptedKey object.
            ek.KeyInfo.AddClause(kin);
            // Add the encrypted element data to the
            // EncryptedData object.
            edElement.CipherData.CipherValue = encryptedElement;
            ////////////////////////////////////////////////////
            // Replace the element from the original XmlDocument
            // object with the EncryptedData element.
            ////////////////////////////////////////////////////
            EncryptedXml.ReplaceElement(elementToEncrypt, edElement, false);
        }

           
            catch (Exception e)
            {
                throw e;
            }
        }


        public static string Decrypt()
        {
                //create XML documentobject and load config file
                XmlDocument xmlDoc = new XmlDocument();

                try
                {
                    xmlDoc.Load("config.xml");
                }
                catch (FileNotFoundException e)
                {
                    Console.WriteLine(e.Message);
                    Console.ReadLine();

                }
                catch (Exception e)
                {
                    Console.WriteLine(e.Message);
                    Console.ReadLine();
                }

                //create container for key
                CspParameters cspParam = new CspParameters();
                cspParam.KeyContainerName = "XML_RSA_FTP_KEY";
                cspParam.Flags = CspProviderFlags.UseMachineKeyStore;
                //create key and store in container
                RSACryptoServiceProvider ftpkey = new RSACryptoServiceProvider(cspParam);
             

                //add keyname mapping qnd decrypt the document
                EncryptedXml exml = new EncryptedXml(xmlDoc);
                exml.AddKeyNameMapping("ftpkey", ftpkey);
                exml.DecryptDocument();
               
                //pass decrypted document to extract credentials method
                string details =  Extract_Credentials(xmlDoc);

                //return decrypted log in details
                return details;

        }

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Any help would be appreciated. Thanks, Darren.

That shows decrypting, but you necessitate to also illustrating how you encrypted the data to start with. If you could construct a single short but complete program which demonstrates that, so that we could reproduce it, that would be immense.