Bizarre PHP error: function not recognizing its own parameter

I have the following function:

  public function updateCustomerInternetBanking($value, $column_to_go_by)
  {
    $sql = "
      UPDATE customer c
        JOIN account_import ai ON c.account_import_id = ai.id
        JOIN generic_import gi ON ai.generic_import_id = gi.id
        JOIN import_bundle ib ON gi.import_bundle_id = ib.id
         SET has_internet_banking = 1
       WHERE c.".$column_to_go_by." = ".$this->quote($value)."
         AND ib.id = ".$this->quote($this->getId())."
    ";

    $conn = Doctrine_Manager::connection();
    $conn->execute($sql);
  }

When I try to run it in development, it works fine. When I try to run it in production, I get this:

PHP Notice:  Undefined variable: column_to_go_by in /var/www/mci开发者_运维百科f/lib/model/doctrine/ImportBundle.class.php on line 655

How could $column_to_go_by be undefined?!

And just so you know, this code is copied straight from production and I checked that the WHERE... line is line 655.

Are you sure you are passing both variables correctly?

A method call like this:

updateCustomerInternetBanking(999);

would produce this kind of error.