I am very much enjoying running through your course, but did come across something I believe to be an error - either that or I have got the wrong end of the stick!
In Question 7 of the exercise for session 6 (using the Data Model, OLAP and MDX) you specifically ask for the Number of Units (Qty) sold by each employee, broken down by month and year. In the screenshot of the result, and in the Answers paper, you summarise the Total Value (Total) field.
Great session, though, and very informative - it really had me dusting off my relational database skills. I'm a trainer and have been asked to get into PowerPivot, so this is a "gentle" introduction!