RuneScape Free-Quest Help!?

I'm doing the Black Knights' Fortress. I got to the part where I have to get into the fortress. Now, I tried disguising my self. I had the bronze med-helm and iron chainbody on, plus some of my other main gear. I tried to go in and they said I wasn't a guard, etc. Then I tried with only the med-helm and chainbody. I got the same message. I waited 5 minutes, then tried again, and still got the same message. I got a friend to help me kill all of the guards, so I could get in. I clicked the door, and a guard from inside gave the the same message. What the heck is going on? I really need to finish this quest for the points. I want Dragon Slayer done, but the requirements are 33 quest points. :(