When one of your comments or posts is 'up-voted' karma is applied to your account. Equally, when your comments or posts are 'down-voted', you lose karma. ... If you monitor your karma, you may notice that the total increases or decreases by a few points. This is done to fool people using vote bots to manipulate the system.
Reddit seems to have mis detected that you might be a troll :S. Reddit has a cooldown on comments and posts. If you post a few comments, then try it once more,... more