trying to blank a dvd with growisofs inside a perl script, it fails. it does not fail when i launch it just in bash:

my $args = "/usr/bin/growisofs -speed=2 -Z /dev/scd0=/dev/zero 1 >> /dvdlog 2>/blanklog.error";
system($args);
in STDERR, i get:
:-[ READ DISC INFORMATION failed with SK=2h/ASC=04h/ACQ=01h]: Resource temporarily unavailable
i've also tried this funny loop, and also making `eject -t` and sleep(3) before launching the command. but what i get is always the same

$growisofsOutputParser="for word in " . '$(cat /blanklog.error | grep -v /dev/scd0);' . " do if [ $word == ':-[' -o $word == '' ]; then echo 'ERROR'; fi ; done";

$growisofsOutputParsed=system($growisofsOutputPars er);
for($i=0;'ERROR' == $growisofsOutputParsed && $i<5;$i++){
system($args);
$growisofsOutputParsed=system($growisofsOutputPars er);
sleep(1);
}