A Tennessee Researcher's disappointment with Finding Your Roots episode

Just now catching up on my DVR'd episodes of Finding Your Roots.  Was disappointed that when they showed Steven King's ancestor's Civil War card, Steven read it as Born in: Kent Co. TN when it was so obvious to me that it was Knox Co. TN.  At first I thought Steven had just pronounced it incorrectly...but then I saw the note card where they feature the run down of the info they had found and they had written it as Kent Co. TN.  I don't understand several things...first off why did they not catch their error when they consulted map or gazetteer and secondly why did they not call in someone who worked extensively with TN records.  Why was this not done prior to the revealing to Mr. King?  Still love the show...but disappointed.