У меня ошибка при проверке XML-схемы:
XmlDocument xmlToSign = new XmlDocument ();
xmlToSign.LoadXml (no.OuterXml);
SignedXml docXML = new SignedXml(xmlToSign);
docXML.SigningKey = NFe_Rec.ClientCredentials.ClientCertificate.Certificate.PrivateKey;
Reference refer = new Reference();
refer.Uri = "#" + no.Attributes["Id"].Value;
refer.AddTransform(new XmlDsigEnvelopedSignatureTransform());
refer.AddTransform(new XmlDsigC14NTransform());
docXML.AddReference(refer);
KeyInfo ki = new KeyInfo();
ki.AddClause(new KeyInfoX509Data(NFe_Rec.ClientCredentials.ClientCertificate.Certificate));
docXML.KeyInfo = ki;
docXML.ComputeSignature();
i++;
xml.ChildNodes[1].ChildNodes[i].AppendChild(xml.ImportNode(docXML.GetXml(), true));