non-working quest

I have quest to get Quel'Delar. I already did most of the quests for this weapon but i have problem with second last quest - when i "Sanctifying" Quel'Delar system doesnt see it.
Can you please help me to fix this problem? Or how I can fix it by myself?

Don't do it in a raid group.

I can't go to sunwhell without raid party

Zoom Zoom Zoomer. Did you eaven read the quest text? You dont need to go in.