PHP mysql PDO refuses to set NULL value

I am unable to set a nullable field with a default value of null to null using mysql pdo. I can do it using straight sql.

I have tried: (mostly from this question How do I insert NULL values using PDO?)

1. Null Int

   bindValue(':param', null, PDO::PARAM_INT);
   

2. Null Null

   bindValue(':param', null, PDO::PARAM_NULL);
   

3. 'Null', Int

   bindValue(':param', 'NULL', PDO::PARAM_INT);
   

4. 'Null', Null

   bindValue(':param', 'NULL', PDO::PARAM_NULL);
   

5. Null

   bindValue(':param', null);
   

6. 'Null'

   bindValue(':param', 'NULL');
   

7. and the bindParam counterparts of 5 and 6 with a variable that held the value of the binding.

Everything from PDO results in the value being set to 0.

PHP Version: PHP 5.3.2-1ubuntu4.10

MYSQL SERVER VERSION: 5.1.63-0ubuntu0.10.04.1

EDIT Screenshot of column info