I really, really doubt that.

Here is the code I tested with, and it's output:

#!/usr/bin/perl 
my %files=%{{1=>"a", 2=>"b", 34=>"c", 5=>"d", 6=>"e", 7=>"f", 8=>"g", 
+9=>"h"}};
my $max;
print join(" ",keys %files),"\n";
grep($max=($_>$max)?$_:$max,keys %files);

print "<$max>\n";
[download]

Output:

perl /tmp/foo 
6 8 1 34 7 9 2 5
<34>
[download]

I don't know what you did to mess up, but it does so contain data, and stores the max.

My guess is that if you try it with your files, you'll find it either works, or your hash doesn't look the way you expect. (Hint: try to output it with Data::Dumper