A dictionary is basically a list of KeyValuePair. You are trying to bind to an enumerable that iterates over each KeyValuePair, not each dictionary. You'll need to flatten the List of Dictionary (List of List of KeyValuePair) into a single List. I'd use the SelectMany extension method. Something like:
actions.SelectMany(dict => dict.ToList()).OrderByDescending(a => a.Key);
There is a great visual example at A Visual Look At the LINQ SelectMany operator. In the example, we have a collection of customers which have a collection of orders, and each order contains a list of items. He iterates over all the items with something like
var flatListOfItems = personList.SelectMany(p => p.Orders).SelectMany(o => o.Items);
The graphics really make the article great, though. You can really see what's happening.