On PS3: Having started the Joining the Legion quest I walked over to to Fort Hraggstad. I killed everyone in both indoor sections, every one on the outside and even shot the archer so he fell off the tower down the cliff. Yet it says that the quest is incomplete and when I talk to the Rikke she tell me to go do the quest. I had previously been at this location before accepting the quest. Also I only noticed the quest was in error, having saved a few time and doing a quest that was on the way back to Solitude. I have no wish of joining the Stormcloaks. What can I do to Complete this quest?

You assistance is much appreciated. Thanks.

I'm concerned about this as well because I just cleared Fort Hraggstad without joining the Legion yet. If possible, you might want to load a previous save and try to join the Legion in another way...which is to say join the Stormcloaks, get the Jagged Crown and give it to General Tullius instead.