Hi,

Rating system depends on map specific rating and your global rating

24/5 on a 5 ppm for 22 minutes won't give you positive rating.
Your kill / death ratio doesn't automatically guarantee a positive rating. For instance, you could have a 30 - 0 rating on a 30 minutes map - but if you only kill one person per minute and the rest of your time hiding somewhere, will give you negative rating.