Saxat från MSDN:
Before you use the ShowFont method, you must set the Flags property of the CommonDialog control to one of three constants or values: cdlCFBoth or &H3, cdlCFPrinterFonts or &H2, or cdlCFScreenFonts or &H1. If you don't set Flags, a message box is displayed advising you that "There are no fonts installed," and a run-time error occurs.