Hi Indraiith,
Make sure ABAP system has profile parameter login/accept_sso2_ticket=1.
Export EP2 certificate SAPLogonTicketKeypair-cert and import into ABAP system, then add this certificate into ACL list using t-code STRUST.
If above are down but issue remains, then send below thing.
1. Tell below property value in EP2 system object.
ITS host name, ITS path, ITS protocol, ICM host name, ICM protocol, Authentication Ticket Type, Logon Method.
2. Tell FQDN of EP2 that you used to do test.
3. Logon ABAP client 100 and execute t-code SSO2, then execute it and send result as screenshot.
Cheers,
Amy