Icewind Dale help pleeease!!!

i just got to the part where im in the basment of the museum at wyrms tooth i have to tell gareth that i will get the key to free the slaves and then talk kerish into giving it to me, but when i talk to gareth the only option i have says"i will talk to you later" and without that kerish says nothing about a key just who are you and join me and find and kill the head slave and i guess without it the middle door at the entrance to the basement stays closed...help please