Exchange 2013 OWA iAPP SSO not working

We have configured OWA 2013 SSO using iApp & following deployment guide to the last word we are getting to the OWA logon page but the SSO is not working,when debug logs are Enabled we are continuously getting below errors in /var/log/apm

Client initiated SSO Loin Failed-Logon Detection match not found.

Also the username in OWA page should be passed as Domain\Username