Attaching filter Problem

Hi all,
I tried to attach an upper disk filter driver using AddFilter (Provided
alongwith the storage group in WinDDK samples).
I got it the wrong way (some problems in my driver I think), now I am not
able to get the drive back(the one on which I attached the driver).
Can anybody explain,
(i) What might be the probable reason.
(ii)What is the solution of this problem
Thanks
Rohit.