I checked paths and filenames, and originally thought it might have been the same problem. As far as I can tell, it seems to be ok for:
vmcrad.org/xcal/01_basic_init.html with a copy of the event XML file.
It is according to internet explorer line 23, char 3, Error ‘scheduler’ is undefined. This line seems to reference the following statement with an editor:
The only situation when such error can occur - js file was not loaded on page
It can be caused by incorrect path in script tag, which referencing dhtmlxscheduler.js