Slider interferes with lightbox, causes data-field to be undefined - with links to test case - colorbox vs flexslider

Slider interferes with lightbox, causes data-field to be undefined - with
links to test case - colorbox vs flexslider

Here is a page with a slider and a set of popup thumbnails. The code is
the same for the tags in both.
http://radiokdug.com/slider-vs-popup-test/?slider=1 clicking on either the
slider or the row of thumbnails results in TypeError: a.data(...) is
undefined
the same page, but without the slider:
http://radiokdug.com/slider-vs-popup-test/
The lightbox popup works fine, without the slider on the page.