Where's the timebox button?

I've been going through the Jazz tutorial (https://jazz.net/learn/LearnItem.jsp?href=content/docs/client-tour/index.html), but have gotten stuck in the Using Jazz Iteration Planning > Time boxing section. I am instructed to "Press the Time Boxing button ... located in the Iteration Plan editor tool bar." On the tutorial screenshots, I see the button between the RSS and Refresh buttons, but on my clients (0.0.0.I20070823-2239 on Windows and 0.6.0.I20070811-1447 on Linux) the button simply isn't there. The time boxing view is exactly what my team needs for iteration planning, but I can't get there . . .