c# - XML signature with x509 sha256 fail -

i want "xml signature x509 sha256 " code give signature (byte[]) ı want signature xmldocument x509 please me

xmldocument docc = new xmldocument(); docc.load("c:\\users\\bera\\desktop\\sertifika\\aa.xml");  x509store storemycurrentuser = new x509store(storename.my, storelocation.currentuser); storemycurrentuser.open(openflags.maxallowed);  x509certificate2 certrca = new x509certificate2("c:\\users\\bera\\desktop\\rca.p12", "0123456789"); if (!storemycurrentuser.certificates.contains(certrca))      storemycurrentuser.add(certrca);  rsacryptoserviceprovider _provider = null;  //doc.outerxml  byte[] data = encoding.default.getbytes(doc.outerxml);  if (certrca.hasprivatekey)  {      _provider = (rsacryptoserviceprovider)certrca.privatekey;      byte[] sigedbytes = _provider.signdata(data, "sha256");      string a= system.text.encoding.ascii.getstring(sigedbytes);      console.writeline(a);