It is hard to say whether or not you skipped a step, but it is important that you compare your results with the Figures in the book, especially with Page 4, the Master-Detail. This page is reference through out the book. Also, refer to the Errata Sheet. How did you do on Reporting on Data from More Than One Table, pp. 81 - 85. This is reference in the Calculation section, pp.94-97. This is a long section and it is very easy to skip a step.
Let me know exactly the page and step where you run into a problem. I will try and assist you as much as I can.
Hope this helps.
Disclaimer: The above comments are solely the opinion of one person and not to be construed as a directive or an incentive to commit fraudulent acts.