Regarding Veritas Volume manager

hy guys
I am new at this thread , i have installed sf 5.0 and wanted to encapsulate root disk but when i get to optionn to enter private region i get this error:

Enter desired private region length
[<privlen>,q,?] (default: 65536) 512
VxVM ERROR V-5-2-338
The encapsulation operation failed with the following error:
VxVM vxencap INFO V-5-2-2635
Usage: /usr/lib/vxvm/bin/vxencap [-F] [-c] [-g diskgroup] [-f format] [-s priv_reg_len] [-N] [medianame=]accessname
/usr/lib/vxvm/bin/vxencap -k -a | accessname...

Can someone tell me what it means and how i can rectify it.
Regards
Charneet

have you tried the default length instead of 512?

yes i have still doesnt work even wit default length