Trouble authorizing new computer for my iTunes account

I have a new computer. Every time I try to authorize it on my iTunes account, it keeps showing "You cannot authorize more than 5 computers". I even tried removing my old phone and ipad from the list but it still does not allow me to authorize my new computer. I only have my iPhone, new iPad, and children's iphones, and 1 computer authorized, which makes a total of 4 iPhones, 1 iPad, and 1 computer authorized. I know I can have 5 computers, and 5 phones authorized. How do I fix this problem?