GVirstor Label problem on -CURRENT

I know it is plenty new code. But I am getting a problem:

./gvirstor label -v -s 2097152 myvol ad8s1d
Total virtual chunks: 524288 (4 MB each), 2097152 MB total virtual size.

Clearing metadata on ad3s1d.
Writing allocation table to ad3s1d... (4 MB, 1 chunks)
Tried to write 4194304, written 4294967295 (Operation not permitted)
Error writing out allocation map!

ad8s1d is unmounted; I tried newfs´ing it but the problem remains;

Yes, I am root, and no securelevel.

Thank you in advance for tha help :-)

-- 
Jazzie Hills