I fiddled around with the IDS and never got an alert going, only to find out that the rules tab seems broken.
The rules loaded from the download tab are not enabled per default and if you enable them, the GUI reflects their setting incorrectly: when a rule is enabled, it does not change state visibly, but after you hit "apply" and reload the page, you can see that they are indeed toggled.
I saw this with Opera and Firefox, most likely this is true for any browser.