Help with nulls?

I need a little help till accounting can get our tech support renewed . . . Running Informix SE 5.00.UD1 and ISQL 4.10.UC2 on SCO Unix 3.2.4. I run the following query and get NO rows retrieved. select wing, floor, room_number, room_long_title from room where building_number = "448" and wing is null and floor = "2"; But I know there is data in there. When I query a different building where the wing is not null, and I say 'wing = "A"', it works fine. After playing around a little, I tried the following for the wing line : and (wing is null or wing is null) It retrieved the data fine . . . WHY!?!?!?!?!?!?!?!?!? Someone else mentioned that nulls in Informix may not be what I am used to with Oracle. Any help/advice/EXPLINATIONS would be appreciated. ___ X OLX 2.2 X Where are we going? And, why am I in this handbasket??