selection expert - blank values

hi,

im developing a report based on a few databse fields. lets say I have many records and that one of the fields in a record is called which can contain one of the following values:

big

small

fat

thin

large

tiny

notice that the 5th values is blank. when i write an sql query on the database, for the fifth field it has: NULL.

In my report, i want let only the records where has on eof the following values

big

thin

notice one of the values is <blank>. However, in the selection expert, it doesnt allow me specify a blank value.

How can I get around this?

Thanks.

J.