Please look at the module DateTime or Date::Calc and replace your code with calls to it.

The following is undebugged and untested, so you're welcome to fix any minor issues that show up. :-)

use strict;
use warnings;
use DateTime;
use DateTime::Duration;
use DateTime::Format::Strptime;

sub timeDiff {
    # invoke isn't used, what's it for?
    my $invoke = shift || '';
    my $date1 = shift || '';
    my $date2 = shift || '';

    my $dParser = DateTime::Format::Strptime->new(
        pattern   => '%F %T',
        locale    => 'en',
        time_zone => 'CET',
        on_error  => 'croak',
    );

    my $dt1 = $dParser->parse_datetime($date1);
    my $dt2 = $dParser->parse_datetime($date2);

    my $dur = $dt2 - $dt1;

    my ($dd, $hh, $mm, $ss) = $dur->in_units('days', 'hours', 'minutes
+', 'seconds');

    return "$dd J $hh H $mm M $ss Sec";
}
[download]