Jail dont work for users

Step by Step:  
- Install openssh-4.3p2 package without errors, all
fine.
- The script in /etc/ssh/sshd_config with a new line:
 Subsystem       sftp   
/usr/local/libexec/sftp-server

- The script in /etc/init.d/sshd was replaced with
another including references to the new compiled (from
the openssh package) binary file:
/usr/local/sbin/sshd.
 The sshd daemon was started using this script.

- All the structure: 
 bin  cssa  dev  etc  lib  tmp  usr  var
was created into /datos/chroot/ and the files into
that directories was maked.

- Then the jailed user was added:
cssa:x:1001:1001:CSSA,,,:/datos/chroot/./cssa:/usr/local/libexec/sftp-server

This configuration work OK for loggin with an SFTP
client. The user home is changed to the
/datos/chroot/cssa and its chrooted to / . This is not
OK. The correct chroot directory for the user is
/datos/chroot/ . 
Of course, I can change to the root directory /, and
this is the problem. I want to limit the user to the
directories over /datos/chroot.
Where is the problem or error?
How I make the chroot directory to /datos/chroot/? 

Thanks for all.
PD: Excuse me for my English.

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