A poll is where Leaderboarded goes off to the metric source and collects score data on your behalf. For example collecting a Klout score for each of your players.
You can fix this by adding more Polls to the Metric Source:
- Edit the Leaderboard
- Go to "Data Sources"
- Click on the Source Name that you wish to enable polling on
- On the edit source page, scroll down and make sure it is set to Auto Poll
- Set the "Number of days/weeks:" to a number greater than 0, you can also change the day/time it does a Poll by editing the "Next poll date/time..." field
Don't forget you'll need to re-release the Leaderboard after it's finished polling and collecting score data.
On standard plans there is a maximum number of polls per month per metric source. This is 5, allowing for one a week.