Ralph, you registration date was June 6, 2012. You first post on record was June 21, 2012. You may have posted between those dates however we can't tell. You may have posted in someone else's topic which was subsequently removed for any number of reasons. If that happened, your post wouldn't be visible any longer. Your personal post may have been removed if it was off topic in the forum you posted in. If you posted the same thing twice or in multiple forums, one post would have been removed.
What I'm trying to say is there are multiple reasons why a post would have been removed but once removed, it cannot be retrieved.