deleting volhist of a databse

[Tae Kim]

i am trying to delete a db backup that resides in a File devclass.  I am running this 
command
 
delete volhist type=dbbackup todate=today devclass=dbbkup_g
 
the dbbackups are couple of days old so they are not the latest.  also we only do full 
db backups
 
I am getting this message: 
 
ANR6978E DELETE VOLHISTORY: Invalid device class DBBKUP_G
 
is it not possible to delete volhist from file dev class?  I have checked to make sure 
the name is right and etc. :(   running a windows 2k version 5.1.6.1
 
TIA
Tae