The record that is missing is most likely the one that does equal. I believe you want to show all items so you should probably use the Caresian (X) symbol in your relationship instead of not equal.
A relationship like this:
Table1::matchField ≠ Table2::Matchfield
with a portal to table 2....
Will not match to a record in Table2 if Table2::matchfield is empty -- even though that means that the value in Table1::matchfield does not equal the Table2::matchfield.
Stacy Chamblee has made the same guess I am, that you need a Cartesian join, but you really haven't explained why you are using this relationship--which I would not refer to as "the traditional relationship".