Error when deleting first Y axis (2D diagram with stacked Y axes)

Hello,

I use a macro for deleting the first Y axis on 2D diagram embedded in a document.
The Y axes are stacked. Initially, the diagramm hat at least two Y axes.

Here’s the code :

Dim objDoc as Document
Dim objDiag as Diagram2D

Set objDoc=ActiveDatabase.ActiveObject
Set objDiag=objDoc.Pages(1).item(1).DocObject
objDiag.YAxes(1).Delete

This code works allways fine except for the first Y axis. The following error occurs :
Err.Number = -2147467259
Err.Description = Erreur non spécifiée
Err.Source = FlexPro
Err.HelpContext = 1000440
Err.HelpFile = C:Programm FilesFichiers communsMicrosoft SharedVBAVBA61033VbLR6.chm

I tried another solution :

Dim objDoc as Document
Dim objDiag as Diagram2D

Set objDoc=ActiveDatabase.ActiveObject
Set objDiag=objDoc.Pages(1).item(1).DocObject
objDiag.YAxes(1).Line.Select
objDiag.Selection.Delete

With this alternative code, sometimes it works, sometimes the following error occurs :
Err.Number = -2147467259
Err.Description = Erreur non spécifiée
Err.Source = FlexPro
Err.HelpContext = 1000440
Err.HelpFile = C:Programm FilesFichiers communsMicrosoft SharedVBAVBA61033VbLR6.chm

I use FlexPro 8.0.21.

Thanks for your help.