Well, several things stand out.

• better practice is to use the three arg form of open: open( LOG, ">", $subject )
• it'd be good to include $! in your error message so you know why the open failed
• it's probably not a good idea to take an arbitrary path from J Random Formsubmitter and use it willy-nilly as a path (and if you're running with tainting enabled Perl should have screamed at you for trying to do so; see perlsec)
• "Perl" is the language, "perl" is the implementation; "PERL" is just wrong