use strict;
use warnings;
use diagnostics;
use File::Copy;

my $htmldir = "C:/wwwRoot/Stats/";

opendir (IMAGES, "Images");
foreach (readdir IMAGES) {
    unless (-e $htmldir . $_) {
        copy $_, $htmldir;
    }
}
closedir IMAGES;

use strict;
use warnings;
use diagnostics;
use File::Copy;

my $htmldir = "C:/wwwRoot/Stats/";
my $sourcedir = "Images";

opendir (IMAGES, $sourcedir) or die $!;
foreach (readdir IMAGES) {
   unless (-e $htmldir . $_) {
       copy $sourcedir.'/'.$_, $htmldir;
   }
}
closedir IMAGES;

copy $sourcedir.'/'.$_, $htmldir or
  die "Error in copying '$sourcedir/$_' to '$htmldir': $!\n";

use strict;
use warnings;
use diagnostics;
use File::Copy;

my $htmldir = "C:/wwwRoot/Stats/";

opendir (IMAGES, "Images");
foreach (readdir IMAGES) {
    unless (-e $htmldir . $_) {
        copy $_, $htmldir or die "Error in copying: $!\n";
    }
}
closedir IMAGES;

Uncaught exception from user code:
    Error in copying: 
 at test.pl line 11

C:\test>perl -MFile::Copy -e "copy('x', 'y') or die $!"
No such file or directory at -e line 1.

C:\test>perl -MFile::Copy -e "print $File::Copy::VERSION"
2.07

C:\test>perl -v

This is perl, v5.8.3 built for MSWin32-x86-multi-thread
(with 8 registered patches, see perl -V for more detail)
...

C:\test>perl -MFile::Copy -e "use diagnostics; copy('x', 'y') or die qq~$!~"
Uncaught exception from user code:
        No such file or directory at -e line 1.