Hi, I have a corporate addin file named test.xlam (on purpose) that when installed,
a custom Ribbon tab will be displayed.

However when I have it as vba syntax in ThisWorkbook module, event Workbook_Open,
it not only displays the tab on ribbon, nor it appears in project explorer:

Private Sub Workbook_Open()
    
    Dim addinPath As String
    Dim xlAddin As Excel.AddIn
    
    addinPath = Application.UserLibraryPath & "test.xlam"
    
    With Application
        
        With .AddIns
            Set xlAddin = .Add(addinPath)
            xlAddin.Installed = True
            'Me.Activate
        End With
    
    End With
End Sub
To get it shown, I have to manually browse and physically add it again:
2018-05-21 17_00_53-Add-ins.png

2018-05-21 17_01_50-Microsoft Excel.png

Thank you for any advice !