Using formatter function of the HTML5 Pro Charts (highcharts) not working

Hi,

I've been trying to use the formatter function of my Stacked Bar HTML5 Chart but it not working though I have respected the documentation.

All I'm trying to do is to hide my dataLabels when the value of the data is lower than 5 : http://joxi.ru/Vm6y4ZdUGvV1rZ

And here is my function : http://joxi.ru/12M15zpiZkqj2J

"function () {if this.y >5 return this.y else return '';}"

I've tried it with the following returns and none of them worked : 

• this.y
• this.value
• this.point.y
• this.seris.value
• this.seris
• this.total
• this.x

Thank you.

Jade