Swipe on mobile

Hello,

I built a simple view with 3 slides. The view is display in a block with the flexslider views style plugin.
Everything seems ok on a normal screen. I can slide with paging and next/previous controls.

But on a mobile device (all browser on iphone or ipad) The slides are not swipable. Yet I enabled the touch option on the config page.

My config is :
drupal 7.26
FlexSlider 7.x-2.0-alpha3
FlexSlider Views Style 7.x-2.0-alpha3
Libraries 7.x-2.1
Views 7.x-3.7
jquery update 7.x-2.3 : jQuery Version 1.7

Any idea if I've done something wrong or if this is a bug?

Perhaps a track : On firefox, when i click on the image, it seems selected (image changes to blue).