business objects - context/joins

Hi,

I've got a three table structure with two 'data' tables and a link
table between them for multiple links to the data tables, with the
left column being keys from the left table and the right column being
keys from the right table. One to many to one. Since there are missing
elements in both data tables, I've set up an alias in the universe and
I'm using a series of outer joins so that reading left to right I get
all the elements in the left table and any items from the right that
appear in the middle table. The alias should provide similar
functionality in reverse.

It doesn't work.

I dumped the alias and the derived contexts and was able to get the
left to right series working. I then put back the right to left
through the joins and it rebuilt the contexts. Still no dice. Now I've
dropped the middle to left join from the alias and i want to see all
rows from the right table and any links to the middle table. Still no
dice.

What the heck does contexts do and how do you access it???? It's a bit
annoying because I can do this in MS Access in about 10 minutes tops.