Yes, Dell uses the same certificate for all SLIC variants so far. In case you want to get your hands on the latest dump of community-discovered OEM certificates (and SLIC binaries), then see here.
Kindly make sure that you flashed the modded image (just for the sake of avoiding human errors), then post a RW-Everything report.
Update Tito: Reflashed with Asus Bios Update tool from with in windows & SUCCESS!! Sorry sir for my issues with proper updating. Thank you.
This BIOS linked above adding (DELL) SLIC 2.6 to the latest ROM for ASRock H97M Pro4 flashed without error and successfully activated (offline) Windows 7 Professional (used Dell cert file and product key). Thank you!