Logout SPID

Buongiorn a tutti,
sto cercando di implementare la logout verso SPID ma ricevo ad esempio Error Code 0 da Sielte.

Di seguito la logout request che invio a SPID:

<saml2p:LogoutRequest Destination="…identity.sieltecloud.it/simplesaml/saml2/idp/SLS.php"
ID="_043622139c53d8204304677d2cb3dc87"
IssueInstant=“2018-08-02T09:06:14.072Z”
Reason=“urn:oasis:names:tc:SAML:2.0:logout:user”
Version=“2.0”
xmlns:saml2p=“urn:oasis:names:tc:SAML:2.0:protocol”
>
<saml2:Issuer Format=“urn:oasis:names:tc:SAML:2.0:nameid-format:entity”
xmlns:saml2=“urn:oasis:names:tc:SAML:2.0:assertion”
>esempio</saml2:Issuer>
<ds:Signature xmlns:ds=“http://www.w3.org/2000/09/xmldsig#”>

</ds:Signature>
<saml2:NameID Format=“urn:oasis:names:tc:SAML:2.0:nameid-format:transient”
NameQualifier=“esempio”
xmlns:saml2=“urn:oasis:names:tc:SAML:2.0:assertion”
>…</saml2:NameID>
saml2p:SessionIndex_aad9ad962a85879ddad175f58cb73c40ea5fd19594</saml2p:SessionIndex>
</saml2p:LogoutRequest>

Ho notato che la request ad identity.sieltecloud.it/simplesaml/saml2/idp/SLS.php va a buon fine, mentre da errore la successiva redirect verso identity.sieltecloud.it/simplesaml/module.php/sielteid/idp/resumelogout.php?id=_87ab6ec5669786412c01f1356ac158dc9d405a7279