The value of Steem has dropped over the past few month, This means your Steem Power does not reward as high a value.
You can see a vote calculator here https://steemnow.com/upvotecalc.html
This will let you see how much your vote is worth.
As the price rises and falls this reflects the reward given to a post, Where previous 200 SP was needed to give a reward at the minimum threshold for a payout of 0.02c has now risen to approximately 500Sp to give the same reward.
To give the same reward now as in previous times you need a SP balance of about 2.5 x the amount previously needed.
I had a look to your wallet, If you convert your SBD to Steem and power up you will double the reward your vote gives,
Its all to do with the current price of Steem. As the price of Steem decreases, then the ammount of your upvote will go down, and as the price of Steem goes up then the ammount of your upvote will go up.
I could go into more depth, but that is essentially how it works!
As steem the currency looses its value your vote value goes down. On todays date you need almost 1100 steem power to equal a $.01 upvote. That is very bad considering any comment that does not recieve at least $.03 does not get a payout and the vote is sent to the dustbin.
You're not alone in these buddy, everyone is affected by the download spiral of the price of Steem.
The value of our votes is directly proportional to the market price of Steem, high price will mean high vote value while it goes the other away around when the price of Steem drop.
Let's just hope that it stops here and start bouncing back-up :)