Are you seeing any errors creating the font, or in drawing the text?

Which version of Imager are you using? If you're using 0.45 you don't need to set the type parameter.

The following worked fine for me on both OS X and Debian stable (x86):

#!perl -w
use strict;
use Imager;

my $font_file = 'Copperplate.dfont';

my $img = Imager->new(xsize=>400, ysize=>300);
$img->box(filled=>1, color=>'white');

my $font = Imager::Font->new(file=>$font_file, 
                 index=>1, 
                 size=>40, 
                 color=>'444444')
  or die "Cannot load $font_file(1): ", Imager->errstr, "\n";

$img->string(font=>$font,
         text=>"This is a test string",
         x=>20,
         y=>50);

$img->write(file=>'test.png')
  or die Imager->errstr;
[download]

Which version of freetype are you using?