GetSMBoundaryBoxDisplayData no Data is returned

Hello.

I've got a drawing wirh a flatt pattern view. I want to get the outline of the BoundaryBox of the flatt plattern view.

For this i thought i can use the Method GetSMBoundaryBoxDisplayData but this method doesn't return any data.

I use this code with a selected flatt patternview. (boundaryBox is not set visible)

Dim swApp As sldworks.SldWorks = CType(GetObject(, "SldWorks.Application"), sldworks.SldWorks)
        Dim swView As sldworks.View
        Dim swSelectionManager As sldworks.SelectionMgr
        Dim swDoc As sldworks.ModelDoc2
        Dim swDrawing As sldworks.DrawingDoc
        swDoc = swApp.ActiveDoc
        'Get the selectionmanager for the document
        swSelectionManager = swDoc.ISelectionManager
        'Get the selected view
        swView = swSelectionManager.GetSelectedObject6(1, 0)
        If swView Is Nothing Then
            Exit Sub
        End If
        Dim dimensions As sldworks.IDisplayData

        swDrawing = swDoc
        swDrawing.ActivateView(swView.Name)
        Dim line1
        swView = swDrawing.ActiveDrawingView
        dimensions = swView.GetSMBoundaryBoxDisplayData()
        Dim linecount As Integer = dimensions.GetLineCount
        Dim x As Integer
      
For i = 0 To dimensions.GetLineCount
            line1 = dimensions.IGetLineAtIndex3(i)
        Next i

The code findes 9 lines. But the data of each line is always -1 (line1 = dimensions.IGetLineAtIndex3(i))

Whats wrong with my code?

SolidworksApi macros