Melee System Mal-function?

I don’t know if anyone else has this issue, however over the past couple of days that i have played Halo 4 War Games; it seems like whenever you try to melee someone directly in-front of them, that sometimes you end up missing and instead end up “showing them your elbow” (lolz).

Again it only happens to me sometimes and yes i am standing at point blank range when i execute the attack in case you guys were wondering.

Any input would be appreciated.