I 've just downloaded the new beta release 1.22 and installed it without any problems 
In the release notes I read something about date search. First I tried the dutch date format (01-01-2008) but nothing happens, then a noticed the date format in de pictures and tried that (01/01/2008) and that did the trick! You have to fill in something like: 24/12/2006-01/01/2008
Maybe it's an option to add a calendar icon into the search field so you can fill in the start and ending date visual and you don't have to remmeber the right date format?
keep on your good work!