drill down when value is 0

Let's say for example we are modeling results on number of sales per country. When you drill down on the country you can see the number of sales per city. However, you want to drill down on the countries that have 0 sales to see what cities are listed as zero in that country. There is also a relationship to another table where it will highlight the salesperson for that city. Since the value is 0 sales I can not drill down on the country to see the cities and also I can not click on the name of the country to have it highlight the sales person in another table. Any ideas?