After completing each chapter, make sure that you are clicking the Mark Complete button located on the upper left corner of the slide. This way your progress will be recorded and the course will allow you to click the Next Lesson button on the upper right corner.

Note: The Mark Complete button is for marking each chapter that you finish as complete. The Next Lesson button is used to navigate through chapters if you are reviewing the chapters only.

To make sure that your progress is recorded and avoid errors with chapter completion, click the Mark Complete button first then click the Next Lesson button to proceed to the next chapter.