Last-Hitting/Attacking Bug

In each game after 10 minutes or so, my friends, others and I have had the same issue regarding base hitting animation. Sometimes the animations goes but the actual attack ceases to go and on the other hand, the attack goes but not the animation. I have noticed this with several champions, such as Karma, Syndra, Veigar, Zed and pretty much all the ad-carries. I would just like to know if it is a problem with my and other's clicking abilities or if it is a bug that needs squashing . Thank to those who respond and to those who don't, well why not?! [slayer-pantheon-thumbs]