SignedXml signedXml = new SignedXml(xmlDoc);
signedXml.SignedInfo.CanonicalizationMethod = "http://www.w3.org/2006/12/xml-c14n11";

System.Security.Cryptography.CryptographicException: Could not create the XML tr
ansformation identified by the URI http://www.w3.org/2006/12/xml-c14n11.