Adding Items to the Toolbox in WF 4.0

I was working through a HOL not following directions (as usual) and I hit an error. The code block was:

ToolboxControl toolbox = new ToolboxControl();
ToolboxCategoryItemsCollection categories = new ToolboxCategoryItemsCollection("My Category");
ToolboxItemWrapper tool = new ToolboxItemWrapper("CustomActivities.Prompt", " CustomActivities", null, null);
ToolboxItemWrapper("System.Activities.Statements.Sequence", " System.Activities", null, "Sequence");

When it ran I would get a run time error at the when toolbox.Categories.Add(categories) executed. The error informed me the System.Activities library was not found. That didn't make a whole lot of sense to me since I had the reference set and the library was most definitely in the framework. After a bit of messing around what I discovered is that at the point of executing Categories.Add() the framework was attempting to resolve the libraries that I had assigned to the ToolboxItemWrappers that I had created and added to the .Tools collection. Modifying the line for the creation of tool2 to be:

ToolboxItemWrapper tool2 = new ToolboxItemWrapper("System.Activities.Statements.Sequence", " System.Activities, Version=, Culture=neutral, PublicKeyToken=31bf3856ad364e35", null, "Sequence");

Gave the framework the right information to find the proper library and load it.