I can't add my macbook pro to iTunes Match.
As I bought my new Macbook Pro (retina) , I want to add my computer to the list with other devices with permission to use iTunes Match. So far , I have four devices (two iPads , an iMac and an iPhone) added , therefore I can add one more , the laptop. But , I don't know why , when I try to add it in my account seetings , iTunes says I have to delete one device in order to add this one. Can anybodo help me , please?
MacBook Pro (Retina, 13-inch, Late 2013), OS X Mavericks (10.9.2)