What are the requirements for successful use of element linking?
I'm creating a report that contains a hierarchy of tables: Sales by Country, Sales by Region, Sales by City, and Sales Orders for City. The user selects a country from the Sales by Country table. The Sales by Region table updates, displaying the regions for the selected country. The user selects a region from the Sales by Region table. The Sales by City table updates, displaying the cities for the selected region. The user selects a city from the Sales by City table. The Sales Details for City table updates, displaying the sales orders for the selected city.
Due to the number of columns and their complexity, I'm leaning towards creating multiple queries (perhaps one for each table, with each query serving as the source for that table) rather than one massive query (that would serve as the source for all of the tables). (I'm unsure of the advantages of one approach over the other. Can anyone comment on that?)
Anyway, when I use just one query, element linking works well: When the user chooses a country in the Sales by Country table, the Sales by Region table updates properly, displaying just the regions for the selected country, etc. When I use multiple queries, however, I can't get element linking to work; rather than displaying the regions for the selected country, the Sales by Region table ignores the selection and continues to display all of the regions for all of the countries.
Are there known limitations in using element linking when the linked elements have different sources/queries, as I described above?