Why has my serious achievement not appeared?

Question

Ok so i have 10,000 kills total in versus ranked matches n no achieve. i have 9,768 in warzone and 248 in execution, NOW WHERE THE F IS MY ACHIEVEMNT. Can anyone explain

Answer 1

The leaders boards tend to glitch my friend also had 10,000 but didnt get  the achievement untill i think around 11,000 somthing it sucks but keep playin you will get it in no time good luck =]