What Tony means by data- attributes is best explained by an example
The HTML of the pencil Icon should look something like this
<a href="#my-modal" data-toggle="modal" data-target="#action_dialogJQ6961" title="Edit">
<img src="/media/com_jevents/images/icons-32/edit.png" alt="Edit"> </a>
but on your site it reads
<a href="#my-modal" title="Edit">
<img src="/media/com_jevents/images/icons-32/edit.png" alt="Edit"> </a>
it is the 'data-' attributes that enable the browser to create the popup to edit the event. It could be a plugin that is stripping this out.