I made changes to the Personal Organizer program as directed by the book and everything worked as the book said that it would. However, I discovered that if I clicked the "Show List" or "Add Person" buttons more than once before clicking the other button then the program would not display the new control (behaved much like it did prior to step 10 in the try it out).
I'm still green enough in VB
2005 that I don't know why this is happening but I did discover how to prevent it; simply nest the code for each button within another If..Then statement. For the Show List button it would look like this:
If objPersonList Is Nothing Then
code as written in the book
If a similar addition is made to the Add Person button's code then each button can be clicked as many times as you want before the other button is clicked and everything will behave normally.