You've made a nice block. But it still comes popping up even though it doesn't return any results! Luckily it is just a matter of settings. Here i'll show you how.

1. In the view of the block you created open up the Advanced options by clicking on 'Advance' on the right.
2. Add a contextual filter by clicking on 'Add' next to 'Contextual Filters'.
3. Now set 'For' on 'This block (override) to make sure this contextual filter is only set for this block.
4. Set 'Filter' on Global to narrow down the results and 'Global: Null' pops up. Select this filter as shown below and click on 'Apply (this display)'.
5. Now select 'Hide view' where it says 'When the filter value is NOT available'. And click on 'Apply (this display)'.

And you're done! Empty blocks will be no more! Thanks to nicoz.

Drupal 7ViewsContextual filtersBlocks