With his guilty plea Wednesday, a Southeast Missouri State University professor admitted he wasn't cheating, only trying to, when he was arrested at Cape Girardeau's casino in December.  66 year old Roger Arpin pleaded guilty to a misdemeanor count of attempting to violate Missouri's riverboat gambling laws and was given a $300 fine plus court costs. Prosecutors amended Arpin's original felony charge to a misdemeanor in exchange for his guilty plea.  Arpin, a longtime literature professor, was arrested at Isle Casino Cape Girardeau in December by the Missouri State Highway Patrol on a felony that charged him with trying to "cap" his bets at the blackjack tables, adding to a bet after the cards are dealt. Arpin appeared before Judge Michael Bullerdieck Wednesday at the Cape Girardeau County Courthouse.