[Plugin: Simple Lightbox] No result

Hello,

I installed (and activated) SLB on http://www.wavetrading.nl/ but nothing has changed. Because there is this Stock Quote widget active on the same page (with a similar pop up effect) I thought this might block the SLB script to work properly, but when I remove it SLB still doesn’t work.
Does anyone have an idea what could cause this?

Thanks a lot for any help!

http://wordpress.org/extend/plugins/simple-lightbox/