Installshield 12 prof. Subfeature selection

[hughcr]

Hi all!

I am trying to set-up an Installshield MSI project that consists of 3
main features, wit one main feature having a subfeature that itself
contains a subfeature :

feature1
feature2
feature3
|---feature3a
|---feature3b

Features 1, 2 & 3 have a level of 100, feature3a has a level of 200,
and feature3b has a level of 300. None of the features are set as
required.

When I build the project, and run a custom installation, I can select
or deselect each of the top level features with no problem.

My problem is that when I select feature 3, feature3a and feature3b
become selected. When I deselect feature 3b, feature3a and feature 3
become deselected. This happens in any combination...

What I am trying to do is:

Select feature3 - feature3a and feature 3b are not selected.
Select feature3a - feature3 is selected, feature 3b is not selected
Select feature3b - all features are selected.

Is this possible? am I misunderstanding something (quite possible, as
this is my 1st Installshield project...)

Any help would really be appreciated... (I have googled and yahooed
and looked at the help documentation, and I just got very
confused :-) )

Thanks in advance!