Everytime you vote, your vote is worth a little bit less. This means that after 10 votes in one day you no longer are able to vote with your full power. the power of your vote depends on how much SP you have, you have got 0.2SP currently. Once you go past 10 votes in one day, your vote will have no power.

Maybe you are voting too much, or you need to invest money into Steem to buy more SP.