you have to do the whole instance in order to get to him. that means you haave to do all of the quests in crimson fields leading up to your incounter with him.
Let me know if I'm wrong, if I'm not this is the right way to do it. You enter the instance. You talk to the people do all the quests until you have to fight Grum Foultooth. You go in and beat him.
That is what you should do. I made this mistake, and as long as its not a glitch just do the above. What you might be doing is going in, rushing to Grum's tower, trying to get in, no way. If that's not what it is you'll have to ask someone else sry. Hope this helped....
