Traceback (most recent call last):
  File "./manage.py", line 11, in <module>
    execute_manager(settings)
  File "/usr/local/lib/python2.6/dist-packages/django/core/management/__init__.py", line 438, in execute_manager
    utility.execute()
  File "/usr/local/lib/python2.6/dist-packages/django/core/management/__init__.py", line 379, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/local/lib/python2.6/dist-packages/django/core/management/base.py", line 191, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/usr/local/lib/python2.6/dist-packages/django/core/management/base.py", line 220, in execute
    output = self.handle(*args, **options)
  File "/usr/local/lib/python2.6/dist-packages/south/management/commands/migrate.py", line 109, in handle
    ignore_ghosts = ignore_ghosts,
  File "/usr/local/lib/python2.6/dist-packages/south/migration/__init__.py", line 202, in migrate_app
    success = migrator.migrate_many(target, workplan, database)
  File "/usr/local/lib/python2.6/dist-packages/south/migration/migrators.py", line 221, in migrate_many
    result = migrator.__class__.migrate_many(migrator, target, migrations, database)
  File "/usr/local/lib/python2.6/dist-packages/south/migration/migrators.py", line 292, in migrate_many
    result = self.migrate(migration, database)
  File "/usr/local/lib/python2.6/dist-packages/south/migration/migrators.py", line 125, in migrate
    result = self.run(migration)
  File "/usr/local/lib/python2.6/dist-packages/south/migration/migrators.py", line 99, in run
    return self.run_migration(migration)
  File "/usr/local/lib/python2.6/dist-packages/south/migration/migrators.py", line 81, in run_migration
    migration_function()
  File "/usr/local/lib/python2.6/dist-packages/south/migration/migrators.py", line 57, in <lambda>
    return (lambda: direction(orm))
  File "{my migration script (South based)}", line 19, in forwards
    posts.update(campaign=F('topic__campaign'))
  File "/usr/local/lib/python2.6/dist-packages/django/db/models/query.py", line 467, in update
    rows = query.get_compiler(self.db).execute_sql(None)
  File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/compiler.py", line 861, in execute_sql
    cursor = super(SQLUpdateCompiler, self).execute_sql(result_type)
  File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/compiler.py", line 717, in execute_sql
    sql, params = self.as_sql()
  File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/compiler.py", line 835, in as_sql
    val = SQLEvaluator(val, self.query, allow_joins=False)
  File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/expressions.py", line 12, in __init__
    self.expression.prepare(self, query, allow_joins)
  File "/usr/local/lib/python2.6/dist-packages/django/db/models/expressions.py", line 110, in prepare
    return evaluator.prepare_leaf(self, query, allow_joins)
  File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/expressions.py", line 35, in prepare_leaf
    raise FieldError("Joined field references are not permitted in this query")
django.core.exceptions.FieldError: Joined field references are not permitted in this query