Does Close Combat Mode Have To Be Done On Assassin?

[iamdemon7]

Complete the game in "Close Combat Mode", any difficulty,The reason i ask is because every time i choose close combat mode it automatically picks assassin difficulty but i can choose whatever & i tried using the glitch that is in this video & it won't pop!http://www.xbox360achievements.org/f...d.php?t=197500 It's the last trophy i need & i don't feel like doing the story for the millionth time!If someone has a solution please don't be afraid to speak!
I did it on easy & followed the video to a t!