Product tabs not loading

Hello.

The product tabs on some of the product pages are not working, for example:
http://www.betson.nl/product/snickers-8001-flexiwork-stretch-fleece-jack/

The tabs on the other pages are working fine:
http://www.betson.nl/product/snickers-6215-ruffwork-katoen-werkbroek-met-holsterzakken/

It don’t get any errors in the console. When I click on one of the tabs other than the first one the div gets a display none, so the script seems to be working fine.
The content belonging to the other tabs is not being loaded at page load.

I don’t know where to look. I’ve disabled all the plugins one by one, but that didn;t help.

Anyone knows where to look?

Thnx in advance!

The page I need help with: [log in to see the link]