I got a raw SQL statement in my views.py

Message.objects.raw('''
        SELECT s1.ID, s1.CHARACTER_ID, MAX(s1.MESSAGE) MESSAGE, MAX(s1.c) occurrences
        FROM
           (SELECT ID, CHARACTER_ID, MESSAGE, COUNT(*) c
            FROM tbl_message WHERE ts > DATE_SUB(NOW(), INTERVAL %s DAY) GROUP BY CHARACTER_ID,MESSAGE) s1
        LEFT JOIN
           (SELECT ID, CHARACTER_ID, MESSAGE, COUNT(*) c
            FROM tbl_message WHERE ts > DATE_SUB(NOW(), INTERVAL %s DAY) GROUP BY CHARACTER_ID,MESSAGE) s2
          ON s1.CHARACTER_ID=s2.CHARACTER_ID
         AND s1.c < s2.c
        WHERE s2.c IS NULL
        GROUP BY CHARACTER_ID
        ORDER BY occurrences DESC''', [days, days])

The result of this SQL statement (tested on database directly) is:

ID  | CHARACTER_ID | MESSAGE | OCCURENCES
----+--------------+---------+--------------
148 | 10           | test    | 133

But all I got is a InvalidQuery Exception with the information Raw query must include the primary key

Then I double checked the docs and read:

There is only one field that you can’t leave out - the primary key field....An InvalidQuery exception will be raised if you forget to include the primary key.

As you can see I got the requested primary key added in my statement. What's wrong?

class Message(models.Model):
    character = models.ForeignKey('Character')
    message = models.TextField()
    location = models.ForeignKey('Location')
    ts = models.DateTimeField()

    class Meta:
        pass

    def __unicode__(self):
        return u'%s: %s...' % (self.character, self.message[0:20])
django django-models
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