I learned after my first week that you can only upvote for a little while before all your steem is used up. This is what happened to me. I could upvote now still, but they would not get anything, and it would only make it be longer before I could upvote and convey any value again. Hope this helps. Wish it were better news....

You need to entice the whales with something that will catch their interest. They ALWAYS have lots of value to convey.