DeleteFiles command error 109

Hi,

I'm having troubles implementing the DeleteFiles command. this is what I use in javascript:

var xmlHttp = new XMLHttpRequest();
xmlHttp.open("GET", 'ckfinder/core/connector/aspx/connector.aspx?command=DeleteFiles&type=Images&FileNames=Image.jpg, false);
xmlHttp.send(null);

But I always get back an error 109 (invalid request). I also tried to use different ways of writing FileNames (e.g. small letters, singular, etc.). Also tried to use POST instead of GET.

Am I missing something here or doing something completely wrong?

Using CKFinder 2.4.2 for ASP.Net

Kind regards,

Johannes