I was recently playing on a factions server and decided I needed more money.  So I began building an underground sugarcane farm.  All was fine until about ten minutes later I noticed the sugarcane still hadn't grown at all.  I have the sugarcane on dirt and the room is four blocks high.  I waited even longer later and still nothing.  Why wont this sugarcane grow?

EDIT: Here is a screenshot:
![enter image description here][1]


  [1]: https://i.sstatic.net/wqJb0.png