Siebel SSO opening sessions only for Anonymous user

Currently we are using LDAP and it is working fine without any issue..But now out requirement is to implement SSO. We tried but URL always opens session with user id which is mentioned as Anonuser in eapps.cfg.

[/service_oui_sso_enu]

EncryptedPassword = False

AnonUserName = GUESTHILP

AnonPassword = XXXXXXXX

TrustToken = HELLO

SingleSignOn = True

UserSpecSource = Header

UserSpec = remoteuser

ProtectedVirtualDirectory = /p_service_oui_sso_enu

ConnectString = siebel.TCPIP.None.None://VirtualServerCER/CER_UAT_ENT/SFSObjMgroui_sso_enu

WebPublicRootDir = E:\Apps\sba81\SWEAPP\public\enu

SiebEntSecToken = aoX1Yesb6KMBaqjGIg==

Please suggest.