Classification specific properties question/problem

Hi, I am an Aras newbie and I am having a problem in following an example from the "Print of Online Help - Aras Product Engineering.pdf" manual p.18  on Innovator 9.1.0:

"To add a class specific property:

1. From TOC, Administration folder, select ItemTypes, search for Part, and open Part for edit.
2. Add a new property, name it Build Number.
3. Click on the Class Path cell of the new property to open the class path form. Select Software, and exit.
4. Save Part.
5. From TOC, Administration folder, select Forms, search for Part, and open the Part form for edit.
6. Click on the properties icon . Select Software's Properties, build_number.
7. Place the new field on the form.
8. Select the Field Physical tab. Uncheck the Visible check box. This property will automatically become visible when a Part classified as Software is created, but will remain invisible for all others.
9. Save, Unlock and Exit from the Part form."

All first 5 steps completed succesfully, but I can't manage to find the "properties" Icon and select the "Software" specific "Build Number" property (step 6 in bold).

I somehow managed to insert "Build Number" as a field, but when I open the form for creation of a new part, it's present even though it's "Software" specifc...

Is there a way to prevent it to appear in the "New Part" form unless I change its type to "software"?

Thank you.

BR,

Alessandro