Ok so i got an order from farkas a companion member to kill the leader of halldir's cairn..! this is the second time to halldir's cairn the first time i had to retrive a drum for someone eveything went smooth... now this second time through the dungeon at the boss part there is a single drugar deathlord so i beat him but the little white quest arrow is still pointing to the center of the gate where you can open up and fall down to the start of the dungeon... i went back to the companions guild and luckily the two other companions still give you work but farkas asks why you havnt got the job done.........any ideas around this.. ?

thank you