See forum post: http://forum.piwik.org/read.php?2,117713

We are on piwik 2.3. I notice the following:

Movers and Shakers
It is not possible to generate insights for this date and period combination.
Insights Overview
It is not possible to generate insights for this date and period combination.

The problem is that we cannot really compare a 'range' date to anything. Imagine you have selected a range period from "Dec 02 2013 - Dec 10 2013". Do you want to compare to "Dec 02 2012 - Dec 10 2012", "Dec 01 2013 - Dec 09 2013", "Nov 02 2013 - Nov 10 2013" or "Nov 23 2013 - Dec 01 2013"? Surely it would be possible to implement to let you pick to which date you want to compare against but it's a bit tricky and just didn't make it into version 1. I'll create a ticket for this but I can't promise it'll be implemented soon.

Related code is here: https://github.com/piwik/piwik/blob/master/core/Period/Range.php#L402