i would strongly suggest not doing that exercise for a few months, and instead going for the other compound chest moves, with dips being my personal suggestion.
i would also take a look at your diet, since without being at all offensive, the weight youre lifting is fairly intermediate, and should have been exceeded (normally) if youre training as hard as you make out. what angle do you have the bench at? how is the rest of your development going? is this exercise/bodypart your problem exercise/bodypart, or are you stagnating across the board? if your other lifts/bodyparts are progressing nicely, then i would abandon this movement. if everything has plateued, then look at general factors like diet, sleep etc
also, some lifts just dont work for some people - i for example can barely do a pull up with the bar going behind my neck, but with other common back moves such as the tbar row, i happily use weight that few others even attempt - and if this is one of those, let it go
sorry if i repeated what others have said, i stopped reading after that other guy started flaming (which there was no need to do, by the way)