Most BB'ers don't have upper pecs development to match the lower portion, so not to worry too much, they can be improved (I pray that no one put's up that illusion of the male pec structure again to show that there is no seperate upper, lower, inner, outter pecs. Those terms are just for points of references ,not actually divisions...most everyone understands it is one muscle unit...we get it!).
Might try incline DB presses with the elbow out and the DB's kepts in line with the neck/jaw throughout the movement. Touch the DB's together at the top but do not completely lock out the elbows. Allow a little tension at the top position. Pec deck, elbows high on the pads and in line with the neck/jaw again. If you decide to do DB fly's than consider cable's instead. DB flys lose most of their benefit about 2/3's (or less) of the way up to the top position. Cables will keep tension on the pec's throughout the exercise. Good Luck.