no check boxes for filtering

[K90267000 via AccessMonster.com]

Hi all,

I am using ACCESS 2007.
when i use want to filter a field,
usually there are check boxes (Select All), (Blanks), a, b, c....blah blah
on some queries, when i try to filter, i can't find these check boxes
(just the normal text filters is available)

May I ask what is the reason?

Thanks!
Ken.