RE:Date filter popup button internal error

Good Day

I'm using the Filtering Table add-on in one of the projects i'm busy with, by the way the add-on is great and i'm using the latest version of vaadin. Everything works fine except for date popup button where you have to set the start date and end date of the filtering,so after selecting the start and end date of filtering i get the following error "Internal error, Please notify the administrator. Take note of any unsaved data, and click here to continue". After that nothing works,so i don't know what might be the problem.

Help please