https://steemd.com/@adipranatahendi/
If you look here you can see your voting power (its currently at 22%). Since you only have 7 steem power plus what is delegated to you, your voting power is too low currently for you to be able to vote.
Accounts recover voting power at about 20% per day. You will need to let yours build back up before you continue voting.
If you had more steem power, then your low voting power would still not effect your ability to vote until an even lower percent. So keep posting and accumulate more power over time. Also remember that you shouldn't vote more than 40 times per day, voting more than that is what wastes your voting power down and causes this to happen.
ok thanks for your explanation... by the way what is this web (https://steemd.com/@adipranatahendi/) i see every my activity in steemit..
It's a different explorer for looking at the steem blockchain.
ohh... this is like blockcain for bitcoin transaction in https://blockchain.info/blocks eh?
sorry iam newbie in steemit.. :)
sort of the steem blockchain does for steemit, what the bitcoin blockchain does for bitcoin (sort of, the steem block chain does a lot more). And yes, steemd is like one of the bitcoin blockchain explorers, but for the STEEM block chain.