After going 2-0 down inside the opening 15 minutes, Rovers fought back as Jeff Hughes netted from the penalty spot and Chris Lines headed home an equaliser. But Charlton went on to score two more goals and Trollope insists the leaks have to be plugged.
"To fall behind so early was a major blow for us, but then we managed to steady the ship," he said. "But our Achilles heel over the last six or seven weeks surfaced again - one cross into our box and a corner and we lost the game.
"We were aware of Charlton's threats and strengths but some of our defending lacked discipline in the opening period. We were selling ourselves and over-eager to win the ball.
"The effort and commitment was fine and some of our forward play was of a good quality, but the details of our defending wasn't right at times and that cost us the game. We can't keep defending like that and things have to improve."