One selection removing other selections unwantedly

[#1]

I have a problem where I have made some selections, but on making a further selection it removes some or all of the existing selections.  Apparently because applying all the latest selection would show zero results. But that is not a bad thing, I would prefer to see zero results than have other selections removed.  Does anyone know how to stop this behaviour?

For example, I may have selected 'Team A' for 'Product Z' for 'Period 1' and a chart displaying a sum of their sales.  If I change the period to one where they made zero sales of 'Product Z', rather than showing ZERO, it removes the 'Product A' selection and shows sales of ALL products.

Any help much appreciated.

[#2]

You may be able to get around this problem by adding in dummy rows with 0s in them to the data set you're working on.

For example, if your data set looks like:

Team,Product,Period,Sales

A,M,1,5

A,M,1,6

A,N,1,7

A,M,2,3

A,N,2,4

A,Z,2,8

you could fix the problem by instead having your data look like:

A,M,1,5

A,M,1,6

A,N,1,7

A,Z,1,0

A,M,2,3

A,N,2,4

A,Z,2,8

It's just null values that QlikView doesn't handle well. If an expression sums to 0 it will display 0 just fine.