Try testing if anything works at all:

open(KK,">$filename") or die "Can't open $filename: $!";
print KK "we are trying to write\n" or die "Can't write to $filename: 
+$!";
close KK or die "Can't close $filename: $!";
system("chmod 666 $filename") and die "Can't chmod $filename: $!";
[download]

And check the server's error log.