You have not activated JavaScript. untermStrich requires JavaScript for operation.
Here are a few important hints in how to set up the most common browsers.
Mozilla Firefox
Select the "Tools" menu -> "Options", and choose the "Content" tab.
Enable the checkbox "Enable Javascript".
Safari
Press "⌘ ," (Windows: "Strg ,") and choose the "Security" tab.
Enable the checkbox "Enable JavaScript".
Opera
Press F12 (Mac: "Alt ⌘ F12") and select "Enable Javascript".
Google Chrome
Select "Options" from the menu and then choose the "Details" tab.
Select "Content Settings" and choose the tab "JavaScript".
Enable "Allow execution of JavaScript for all sites" or add untermStrich to the exceptions.
Internet Explorer
Select the "Tools" menu -> "Internet Options" and choose the "Security" tab.
Activate the security level "Medium".
Select "Custom Level" and choose "Enable" in "Script" -> "Active Scripting".
