No grid lines on X axis

I'm doing some coding to have log-log plots, so I need to specify the ticks values manually. So far, everything is going great on y-axis, but on x-axis I'm having this issue with disappearing grid lines. See this fiddle as an example...only 1 line is appearing, and it's not related to any point of the data.

http://jsfiddle.net/asnj1k4n/2/

How can I make the x grids appear again?