print chart to xps

hello,

i created a chart in a fixeddocument. i used clr-namespace:System.Windows.Controls.DataVisualization.Charting;assembly=System.Windows.Controls.DataVisualization.Toolkit

i have a problem when i print the document. i used this code

        Dim fd As FixedDocument = stampa.FindName("myFixedDocument")
        Dim xpsd As Packaging.XpsDocument = New Packaging.XpsDocument("G:\test.xps", System.IO.FileAccess.ReadWrite)
        Dim xw As XpsDocumentWriter = Packaging.XpsDocument.CreateXpsDocumentWriter(xpsd)
        xw.Write(fd)
        xpsd.Close()

the file printed don't show the barchart. print all except bar.

can anyone help me?

thanks

Marco