[SSJKarma]

that is a simple lagging problem. nothing can be done to get it work better !

explanation:
the game as to sync with your opponent, but the moves you do takes a certain time to get to your opponent computer and be processed, and once it it processed it it sends you the answer to see if you hitted him or not. the time it takes to get across internet is the time delay you get in the game before seeing your opponent damage !

if there was no damage dealt after the lag effect passed, then that means you hitted the air and not your opponent. it may be touching him on your screen, but that doesn't mean you actually hit him.

that's what hapenned.
hope it helped you understand more about this game !