Symmetric Algorithm not specified-- Need urgent help

Hello Everybody,

i have implemented SAML in my MVC application. it is working fine but when i deployed in production server i am getting error "Symmetric algorithm not specified" near SAML response xml decryption time.

Below is my code.
system.security.Cryptography

private void Decrypt()
{
// Check the arguments.
if (xmlDoc == null)
throw new ArgumentNullException("Doc");

// Create a new EncryptedXml object.
EncryptedXml exml = new EncryptedXml(xmlDoc);

// Decrypt the XML document.
exml.DecryptDocument();
}
Thanks in advance