Have you sent your findings to the lead editor at AP? I'd say he's got a reporter that needs firing.
Dear AP:
You might want to take a second look at your story on Ben Barnes and how he helped get Bush into the Air National Guard when he was Lt. Governor of Texas. It appears that Mr. Barnes didn't become Lt. Governor until 1969. In 1968, he was U.N. Representative to Geneva, Switzerland. Here's a link to a website of his biography:
http://www.klru.org/texasmonthlytalks/archives/barnes/bio.asp
I do expect a correction and maybe a job offer for doing the job your reporter didn't.