filter by form

[Gisel]

Hi, hoping you can help me.

I have a form that when i click "filter by form" a blank
form opens. The problem i am having is that when i click
on some of the fields on the filter by form the field
gives me a drop-down list of all the entries for that
field but for other fields it just says "null" or "not
null". Can you tell where the setting is to make all the
fields in a filter by form show the list of entries that
have been inputted when you click on the field.

Thanks for any help!
Gisel
(e-mail address removed)