Why weren't Kise and Midorima able to get in the Zone?
Kise 


   has already been shown to enter the Zone in the fight against
 Jabberwock. (Read: Kuroko no Basuke: Last Game)


During his state, he can freely copy all moves including moves that he wasn't capable of using, which were moves by Generation of Miracles-tier. 


   He used the Zone in conjunction with his Perfect Copy Ability amping
 up all the skills he currently has.


It is stated in the manga that those who have a passion for the game can enter the Zone. This is shown that even though it appears that Murasakibara had shown a dislike for basketball, that he also, indeed loves to play basketball too. This is one of the pre-requisite to enter the zone.

Knowing Midorima, he can't enter the Zone as he is as of now. He thinks of basketball as nothing more than just a game that he's good at. There's a probability that he can enter the Zone considering he is already is a GoM. All he has to do is to have strong passion/love for Basketball.