I've checked your code. It runs when I reverse your comments, as follows:

my $octets_out = '1.3.6.1.2.1.1.3.0';
#my $octets_out = 'interfaces.ifTable.ifEntry.ifOutOctets';
[download]

Not surprisingly, I got a message telling me that host 1.2.3.4 wasn't responding, but it certainly is a hopeful indication that you're on the right track.

Could it be that your code (as I changed it) was working, but you thought it was hanging because it was timing out?