This may have to do with not clicking the 'I'm Done'-button. Even when you have the lesson at 100%, (and MeneerZwijn is right, there are only 5 chapters) they don't show up in the 'My Guitar Tricks' as a completed percentage of the full course.
You can check here (http://www.guitartricks.com/course.php?input=1) to see what things you lessons at 100% and which you have completed (by marking it as 'I'm Done')
Hope that helps.
JJ