If you get something similar with Perl 5.8 then this might help to figure out what exactly is wrong.

Alas not. The extra data you see is missing from 5.8.8:

$ perl -v

This is perl, v5.8.8 built for x86_64-linux-thread-multi

Copyright 1987-2006, Larry Wall

Perl may be copied only under the terms of either the Artistic License
+ or the
GNU General Public License, which may be found in the Perl 5 source ki
+t.

Complete documentation for Perl, including FAQ lists, should be found 
+on
this system using "man perl" or "perldoc perl".  If you have access to
+ the
Internet, point your browser at http://www.perl.org/, the Perl Home Pa
+ge.

$ cat uninit.pl 
#!/usr/bin/perl

use strict;
use warnings;

my ($DIcas_text, @HR, $s);

$DIcas_text = "%s %s %s %s";
@HR = qw(a b c);
$s = sprintf($DIcas_text, @HR);

$DIcas_text = "%s %s %s";
@HR = ('a', undef, 'c');
$s = sprintf($DIcas_text, @HR);

$DIcas_text = undef;
@HR = qw(a b c);
$s = sprintf($DIcas_text, @HR);
$ ./uninit.pl 
Use of uninitialized value in sprintf at ./uninit.pl line 10.
Use of uninitialized value in sprintf at ./uninit.pl line 14.
Use of uninitialized value in sprintf at ./uninit.pl line 18.
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