problems with MAC labels on files

[Gabor Kovesdan]

Hi,

I'm trying to set up an MLS policy but I'm unable to label files. 
Multi-label option is enabled on /, UFS_EXTATTR and 
UFS_EXTATTR_AUTOSTART is in the kernel and the MLS module is loaded.

# uname -a
FreeBSD .localdomain 8.1-RELEASE FreeBSD 8.1-RELEASE #0: Mon Dec  6 
00:20:31 WET 2010     
gabor at .localdomain:/usr/src/sys/i386/compile/GENERIC  i386

# setfmac mls/20:1 test
setfmac: labeling not supported in test

I've read all the documentation and man pages but I cannot find what 
else do I have to do to get it working. Could you please tell what I'm 
missing here?

Thanks in advance,
Gabor Kovesdan