Hi Amer,
You seem to have an issue on the Client. Could you check the output of the command "klist" on the client side? If you did not get a ticket for the service user you have configured for SPNego, then the issue is between your Client and your AD and not the Client and your ABAP server.
You can check if the Client is in the same domain as your AD or in a sub domain. If the client is in a sub domain, you have to create a keytab using the transaction SPNEGO for this sub domain too (No need to create a new Service account).
KR
Valerie