Hi Sid,
This is the actual what is happening in SCN. Anyone will never able to receive any points when (s)he will mark his/her own reply as correct.
Even though it is applicable for moderator also.
Fortunately one interesting thing is that, if someone mark his own reply as correct then he will not receive any points but if the same reply unmarked as correct by moderator, then he will loss 10 points (which he didn't receive that)..
Regards
DP