Welcome to the wonderful world of TSO, where the developers believe in 'luck' to complete quests. Even really important, time-limited quests.
This quest is notoriously difficult to complete. Even on the test server with 10 experienced explorers it took me two weeks. On the live server it took even longer. You could always ignore it for a while and crack on with something else, and come back to it later. If I recall correctly, it's not a hugely important quest.