Try: use Data::Dumper at the beginning of your code and then print Dumper(\@vars) at the end. This should give you a clue on what is in the @vars array. By the way the doc for Net::SNMP says the -varbindlist parameter should be a reference to an array: -varbindlist      => \@oids not a string, I have never used this module so I can't tell, but it seems suspicious.