poll-billing.php and or schema mismatch issue

Timestamps are not getting entered for bill in/out port data. DB schema has field type as timestamp but INT is attempted to be entered. Timestamp is a not null and defaulted to current timestamp so simply commenting out the timestamp part of the SQL statement in PHP on poll-billing.php seems to fix the issue for me.

Here is my code with commented out timestamp and attached image of my timestamps now getting udpated.
dbInsert(
array(
'port_id' => $port['port_id'],
//'timestamp' => $now,
'counter' => $data['in'],
'delta' => $in_delta
),
'bill_port_in_data'
);
dbInsert(array(
'port_id' => $port['port_id'],
//'timestamp' => $now,
'counter' => $data['out'],
'delta' => $out_delta
),
'bill_port_out_data');