Method to maximizing MPlaceolder fail, parent of MArea is null

Question

In my project I use MArea with PartStack as Shared Elements. Perspective contains Part Sash Containers with Placeholders having references to MArea from Shared Elements. The problem is Maximizing, press Maximize button do change icon and tooltip only. Minimize and restore after works prefect. I found that the problem is getParent() method returns null when asking for MArea.

img of Application.e4x