Automatically set window transparency in 11.1 KDE?

I want to set the default transparency for specific windows, using a 11.1 KDE4 KWin desktop. I found the Configure Desktop->Window Behavior->Window Specific interface, which looks like exactly what I want to create rules based on specific window types.

I can easily create a rule by using the ‘Detect Window Properties’ button to select a window (using window class) and set the opacity under the Preferences tab to Force 70% and apply the rule.

However, after numerous tries with different app windows (KNotes, Konsole, etc.) I have never seen a rule have any effect, the specified windows are always at opacity 100%.

All my animation effects work fine, and I have the mouse wheel set to change opacity manually, which also works fine, but I’d like to have these rules be effective and set opacity automatically for specific windows. I’m fairly sure I have the rules defined correctly and have experimented with less specific rules but in no case have I seen them have any effect.

What am I misunderstanding or doing incorrectly here?