In an effort to crack down on stores that sell alcohol to minors, state police conducted an undercover sting Thursday on more than a dozen stores in Putnam and Dutchess counties.

In each case, police say they sent in a 19-year-old male to buy alcohol. The teen was successful in 10 of the stores.

Pete Knapp, owner of Pete's Hometown Grocery, insists his employees always know to card anyone buying beer. In this case, he says one of his workers made an honest mistake and did the math in his head wrong.

Other stores busted in the sting say it was simply an oversight, and that there was a lot going on at the time the teen came into the store.

All the clerks in the stores were charged with misdemeanors. The owners now face civil penalties.