javascript: Flot charts hidden render

this is my first question here :) Sorry for my bad english je je

Im using flot charts in my website and im having problems trying to render a chart in a hidden tab but i dont know why!

In the tab "Estadisticas" (is hidden at loading) when you press it, it show the chart, but the Y axis labels is INSIDE the chart.

I look in examples, in the wiki, in Google, in stackoverflow (ofc) but i dont know where is the problem.

Thanks.

javascript