PHP issue insert with auto_increment - php

Question

I'm pretty new to PHP code.
I have a tabel that I want to insert in to but for some reason the insert statement does not work. The tabel has an ScanID column that AUTO_INCREMENT 's. I've tried a few things like just leaving the ScanID out of the statement but that didn't work either ( I also tried swapping the NULL with ' '). I was able to insert in to other tables where there isn't an ID that AUTO_INCREMENT's so my pretty sure that my connection works.
<?php
$xml=simplexml_load_file("someFile.xml");
$con =new PDO("mysql:host=localhost;dbname=testDB",'root','');
$ScanType="someType";
$start_date=$xml ->start_datetime;
$end_date=$xml ->finish_datetime;
$TargetTargetID="1";
$stmt=$con->prepare('insert into
Scan(ScanID, ScanType, start_date, end_date, TargetTargetID) values
(:ScanID, :ScanType, :start_date, :end_date, :TargetTargetID)');
$stmt->bindValue('ScanID',NULL);
$stmt->bindValue('ScanType',$ScanType);
$stmt->bindValue('start_date',$start_date);
$stmt->bindValue('end_date',$end_date);
$stmt->bindValue('TargetTargetID',$TargetTargetID);
$stmt->execute();
$ScanID=$con->lastInsertId();
echo $ScanID;
?>
EDIT: this worked for me
$stmt=$con->prepare('insert into
Scan(ScanType, start_date, end_date, TargetTargetID) values
(:ScanType, :start_date, :end_date, :TargetTargetID)');
$stmt->bindValue('ScanType',$ScanType);
$stmt->bindValue('start_date',$start_date);
$stmt->bindValue('end_date',$end_date);
$stmt->bindValue('TargetTargetID',$TargetTargetID);
$stmt->execute();

Answer 1

No need to pass auto increment column value in insert query just remove from columns and values to
$stmt=$con->prepare('insert into
Scan(ScanType, start_date, end_date, TargetTargetID) values
(:ScanType, :start_date, :end_date, :TargetTargetID)');
Remove from bind values
$stmt->bindValue('ScanID',NULL);