New glitch in Waking Nightmare?

[Stoneage]

I've found the potion Vaermina's Torpor but the next script has never been triggered:

 

Your next stop will be the Laboratory, where Vaermina's Torpor should be stored. 
   There are some more Invader Orcs and Vaermina Devotees that will need to be dealt with 
   as you go along. When Vaermina's Torpor is located, Erandur instructs you to drink it 
   and upon doing so, you become Casimir, a Vaermina Devotee during the Orc raid on the 
   temple. You are instructed to release the Miasma to protect the Skull. 

 

I've tried to reset the character to no avail:

   
   It is possible that reseting his location to the player will resolve this issue (open 
   the console and type "prid 0024280" and then "moveto player").

When I try to drink the potion I receive the message:

   Quest item cannot be eat.

Similar happens when I try to remove it:

   Quest item cannot be remove from inventary.

How can I solve the quest?

Edited December 30, 2011 by Stoneage