Unable to change font family

The following code prints correctly the font name and index.

        Fonts fonts = templatePres.getFonts();
        for (int i = 0; i < fonts.size(); i++) {
            FontEntity fe = fonts.get(i);
            System.out.println("Name="+fe.getFontName()+", index="+fe.getFontIndex());
        }

Name=Arial, index=0

Name=Tahoma, index=1


But when I change Arial to Tahoma, I still see Arial in the Presentation. Could it be a bug in Aspose.Slides? Please advice.

        Paragraph p = shape.getTextFrame().getParagraphs().get(0);
        Portion pt = p.getPortions().get(0);
        pt.setFontIndex((short) 1);

Do you have any comments about this issue? thanks a lot.

Could you attach your ppt please?

Hi Alexey, before attaching the ppt files I checked once more and found out that the copied Presentation had different font indexes.
The original has:

Name=Arial, index=0
Name=Courier New, index=1
Name=Tahoma, index=2

and the copied Presentation has:

Name=Arial, index=0
Name=Arial, index=1
Name=Courier New, index=2
Name=Tahoma, index=3

I wonder why 2 Arial fonts? anyway I got the new font index, and it worked nicely.
Thanks for your help