[Samba] tab key does not complete the package name or list the packages in apt-get command

[Muhammad Yousuf Khan]

i am using debian 6.0.7.
in my other debian machines when i type "apt-get install sam<tab>" it give
me all item start from sam and this is a default behavour. however now for
some reason <tab> key is not working. is there anyone know why.

note: for other commands <tab> key is working fine.

Thanks,

Myk