invert selection of the below script is not working, someone help

the selected property is to be used only with an object, it doesn't work for selection.

This is a code in C#, which performs the procedure, someone from VBA can easily rewrite it for you

[CgsAddInMacro]
public void InvertSelection()
{
    ShapeRange selectedRange, allRange;
 
    selectedRange = corelApp.ActiveSelectionRange;
    allRange = corelApp?.ActivePage.Shapes.All();
 
    allRange.RemoveRange(selectedRange);
    selectedRange.RemoveFromSelection();
    allRange.AddToSelection();
 
}

Hello, 
I test this code in CorelDRAW X5 and he work for me well.

I can not understand reason for not working?!

Please explain what happens if not working? Please write error message and row of code where macro stops!

Greetings!