This problem can easily be fixed, thank goodness for that. :) I've had the same problem, and I can say that most players have. After raging and raiding Quest "help" sites, I spotted one small sentence that could actually help you progress through this quest. Easy to miss and easy to ignore, especially if you are as impatient as I am ;). So, firstly, don't bother going back to Drezel or talking to Filliman again ... and again ... and again =_=. No! Ignore that old fool. To put it simply, all you must do is stand on the orange stone "while" and I repeat "WHILE" you are talking to Filliman or else the puzzle won't be "COMPLETE"! Once standing on the orange stone select the dialogue that says you've completed the puzzle. Filliman will do his magic trick and he will "finally" be able to become a nature spirit, and you will able to access the grotto.
