Get a Max and Min using CountDistinct

Hi,

I hope you can help me with this issue, i'm new on SSRS and I got stocked in this issue.

I'm working with this tablix with Row (Country) and Colums (Topic) and Data = [CountDistinct(Question_key)].

I would like to have something like this:

Sports FoodTravel MinMax

Colombia5 4225

Argentina81 318

But using the CountDistinct aggregation expression in the Min (Min(CountDistinct(Fields!Question_key.Value)) and Max (Max(CountDistinct(Fields!Question_key.Value)) I get something like this: 

Sports FoodTravel MinMax

Colombia5 421111

Argentina81 31212

I found this link with the same question but after some posts the Question wasn't solved. Min and Max of a count based on a grouping

Please can anyone help me? I'm using SQL 2012.

Luis Carlos