Details button not working

When I click the details button of an event on the schedule nothing happens. In the Javascript window (Chrome browser) I see the errors below. I’ve tried this in IE8 an IE9 – same result. I’m wondering if there is something on my website preventing the lightbox from opening, although i have other lightboxes ont he site that work fine.

Uncaught TypeError: Cannot call method ‘toLowerCase’ of undefined dhtmlxscheduler.js:46
d dhtmlxscheduler.js:46
f dhtmlxscheduler.js:48
g dhtmlxscheduler.js:49
i dhtmlxscheduler.js:50
dhtmlx.modalbox dhtmlxscheduler.js:51
scheduler.showLightbox dhtmlxscheduler_recurring.js:24
scheduler._click.buttons.details dhtmlxscheduler.js:88
scheduler._click.dhx_cal_data dhtmlxscheduler.js:86
scheduler._click.dhx_marked_timespan.scheduler._click.dhx_cal_data dhtmlxscheduler_timeline.js:37

Hi,
it’s incorrect behavior. Could you provide link to your scheduler page?