newfs ing wtih PERL -- dont work

[Todd Gruhn]

            my ($arg1 , $arg2);

            $arg1 = " dev=/dev/rcd0" ;
            $arg2 = " blank=fast" ;

            open(FH, '|-') || exec("/usr/pkg/bin/cdrecord" . $arg1 .
$arg2); ## WORKED

                                        ##  BETTER?

            close FH;

            sleep 2;

              my ($arg3 , $arg4 , $arg5);

                  $arg3 = " -L BIGDISK" ;
                  $arg4 = " -F -s 4.7G" ;
                  $arg5 = " /dev/rcd0d" ;

      open(FH, '|-') || exec ("/sbin/newfs_udf" . $arg3 . $arg4 .
$arg5 ); ## BUUUT!

                                        ## This dont word

            close FH;


I type it in by hand -- it works. IF PERL newfs the DVD, it  dies.
What is wrong here; what is the best way to do this??
I do this in a root-prigram...