Unicde characters don't show up even with utf8 encoding

On one computer, this works fine.

On another computer these lines defining the fonts:

$headerfont = $pdf->corefont( "Helvetica-Bold", -encode=>"utf8"); 
$font = $pdf->corefont( "Helvetica", -encode=>"utf8"); 
$italicfont = $pdf->corefont( "Helvetica-Oblique", -encode=>"utf8"); 

Then when using a unicode character for trademark or bullet... they
don't show up.  

Does this mean the corefonts on that computer don't support
unicode????  Or is it a problem with my syntax?

-Tim