Halo:Reach- How to get If They Came To Hear Me Beg Achievement

[dont4getthis11]

I don't understand why it is I cannot earn the achievement.

I've assassinated him a dozen times however it does not unlock the achievement when I do it.

I'm on legendary and such, so I'm thinking it's a problem with my using the sprint ability?

How exactly are you supposed to stop using it so the achievement counts??

[lSmGProductionsl]

@dont4getthis11 The first time i tried it i got it, But one of my friends told me he had to assasinate him a second time somehow because the achievement wouldn't register, Try changing your control schemes to recon so you meelee with B instead of RB i heard some people tried that and got it.