Bash Completion Problem with sudo on Ubuntu VPS

I have a VPS from Linode. I deployed Ubuntu 10.04 server. I added a user and put it sudoers file.
when I write as a user

apti <TAB>

it comletes with tab to

aptitude <TAB>

but when I continue to

aptitude upd <TAB>

it didnt complete but on my desktop it works great. Even
worse if I try same command with sudo

sudo apti <TAB>

does not work
I checked .basrc, .profile/.bashrc and /etc/bash.basrc files
and none of them were commented out so what is wrong.
By the way when I root it works

mine ~/bashrc

if [ -f /etc/bash_completion ] && ! shopt -oq posix; then
    . /etc/bash_completion
fi