An exciting game at Saltergate in difficult conditions saw the Reds run out 3-1 winners, although the result was in doubt up until a late third goal by John Thompson.
O'Hara told the Chesterfield website: "I thought we were unlucky today.
"I thought we were on top of them for most of the game. We were confident; we've seemed to play well against the better teams, but silly goals are costing us at the moment."
