Your logic seems OK. This simulates what you are doing and works fine:

%hash = ('subjects' => "foo\n",
         'bar'      => "baz\n");

$job_hash = \%hash;
print $job_hash, "\n";         # add this
print $$job_hash{'subjects'};  # add this
$$job_hash{'subjects'} =~ s/\n/<br>/g;
print $$job_hash{'subjects'};
[download]

To debug it I would add the two lines noted to ensure you have a hash ref and that the data is what you expect before you try to modify it. As the code above works fine (on a hash ref) this should help you identify the source of the problem.

cheers

tachyon

s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print