Kindly refer to this link: Netflow on ASA - Cisco Support Community
It says there: "The implementation used on the ASA platforms is NetFlow v9 which is defined by . The feature was introduced in ASA 8.2.1/ASDM 6.2.1." So if you are using version 8.0, you need to upgrade at least to version 8.2.
Thank you for your reply Sirpaw. I see that to be our wayfoward.