For some reason I cant report suspects as DOA. The option is greyed out even when putting the crosshair on them, I know that I used to be able to do this with my original copy.

If one of your teammates kills a suspect they may report them DOA themselves and then the option to report them as being neutralized will be greyed out. You will only be able to falsely report them as down (wounded).
Your teammates never report suspects that are down or ready to evacuate. They only report neutralized suspects, but sometimes they forget to do it themselves.

I noticed this a while back too mate when I had got it off a torrent to start off with.
I think its due to the AI just does it now, I use to have the very original one that came out in the 97 or 98 or so on disc.
I think it was just one of the many changes in the elite version