A very simple thing with a very annoying problem.

As explained in almost every tutorial on the web i just did this:
- built and populated my DB
- created an UltraGrid, ViewStyle set to MultiBand
- created a new DataSet
- created a parent DataTable, filled by a query. Let's call it A
- created a child DataTable, filled with a query, Let's call it B. B has a foreign key referencing A's primary key
- added both tables to my DataSet's Tables
- created a DataRelation between A's primary key column and B's foreign key column. Here is the code:

oRel = New DataRelation("suppItems", _
ds.Tables("anaSupp").Columns("anaSuppID"), _
ds.Tables("anaItem").Columns("anaItemSupp_ID_anaSupp"))

- added oRel to my DataSet's Relations
- set my DataSet as my UltraGrid's Datasource.

My DB is correctly populated, A and B are correctly created, oRel is created.
Nonetheless when i run my project, if I click on the + icon to the left of A's rows, nothing is displayed. The same if I set A as DataSource.

Why?