It works fine here. Here is what I've done:
- Create an entity with one attribute of type boolean.
- Create a form
- Add a data view connected to that
entity.
- Add a tab control inside the data
view.
- Select the first tab page.
- Edit the property 'Condition' of
that page.
- Check 'Make tab page conditionally
visible based on attribute value'.
- Select the (only) attribute of the
entity.
- The conditions grid is filled with
attribute values true and false.
Did you place the tab control INSIDE a data view?