can't add more than 4 grouped products to a course

Is there some kind of limit set on the group products? I am able to add these 4 to the course page I set up http://www.communitelligence.com/product/becoming-an-authentic-strategist-course/ but cannot add the 5th which is a product to sell the complete course: http://www.communitelligence.com/product/part-4-building-influence-increasing-acceptance-copy/ Am I missing something? the complete course is set up as a simple product like the other 4 so can't see why this doesn't show. Help please.