Office Mac Home and Student 2011 Product Key Invalid

I just downloaded Office 2011 home & student. Word and Excel are up and running fine, but when I clicked on outlook the Microsoft Office window opened asking for my product key again. When I entered it, it came up invalid. This was a family package which I used the last product key. Not sure why it's asking for it again after Office has been completely downloaded already and the rest of it is working fine.