Migration Problem

I get the following exception when I attempt to migrate:

.../South-0.7.2-py2.6.egg/south/migration/__init__.py", line 88, in checkk_migration_histories
  raise exceptions.GhostMigrations(ghosts)
south.exceptions.GhostMigrations:

 ! These migrations are in the database but not on disk:
    <askbot: 0021_auto_add_field_comment_score="">
 ! I'm not trusting myself; either fix this yourself by fiddling 
 ! with the south_migrationhistory table, or pass --delete-ghost-migrations
 ! to South to have it delete ALL of these records (this may not be good).

Note that I had a fairly old verion (0.6.17) and am migrating to 0.6.47 This is also using the virtualenv.

This is using mysql as the DB.