Sounds like invalid clicks. On the flipside, you'll smile when you make a couple of dollars for no clicks at all, lol
I know its tough, but as others have said you need to be patient. It is really difficult when it starts off like this, but it will be worthwhile in years to come...just keep at it! Most of my clicks are in the $1-2 range, but occassionally I will get the 3 or 4 clicks for a cent or something ridiculous. It is most probably invalid clicks..
Probaly due to the click did not lead to a conversion. Try increase clicks and traffic and you should start seeing some earnings coming through.
Probably you just got click from ip that has use to click other adsense ads before , this can happen ..