Top Download's script, I can't run ........I need help.

why i can't run the top download's download.pl script??? when i ran it with browser, it views 500 error(server error),when i ran it console, it says No such file or dictionary..

why...i can ran other .cgi/.pl script, ex. sample.pl/basedir.cgi(below).

[root@linuxserver cgi-bin]# ls -l
total 88
-rwxr-xr-x    1 root     root          111 Feb 23 10:43 basedir.cgi
-rw-rw-rw-    1 hgkrt    hgkrt           0 Oct 11  2000 daylog.txt
-rwxr-xr-x    1 hgkrt    hgkrt       30175 Feb 23 13:50 download.cgi
-rwxr-xr-x    1 hgkrt    hgkrt       30230 Feb 24 09:43 download.pl
-rw-rw-rw-    1 hgkrt    hgkrt           0 Oct 11  2000 download_stats.txt
-rw-rw-rw-    1 hgkrt    hgkrt           0 Oct 11  2000 log.txt
-rwxr-xr-x    1 hgkrt    hgkrt         174 Feb 22 19:47 sample.pl
-rwxr-xr-x    1 hgkrt    hgkrt        5736 Apr  5  2002 stat_js.pl
-rwxr-xr-x    1 hgkrt    hgkrt        5435 Feb 22 09:45 status.pl
[root@linuxserver cgi-bin]# ./download.cgi
bash: ./download.cgi: No such file or directory
[root@linuxserver cgi-bin]# ./download.pl
bash: ./download.pl: No such file or directory
[root@linuxserver cgi-bin]# ./sample.pl
Content-type: text/html

<HTML>
<BODY>
<TITLE>CGI Script TEST</TITLE>
</BODY>
The CGI script was worked!
</HTML>
[root@linuxserver cgi-bin]#

when i changed the first line of download.pl : #! /usr/lib/perl to #!/usr/lib/perl --

it runs.

why i add the --, it can run ?

4.To count a download use:
<a href="download.pl?file=filename_id">yourfile</a>
"filename_id" can be a number or a string.

and where to add the count???