Why my Pr CS6 licence conflicts with my Pr CC subscription

When my CS6 Encoder was destroyed by CC installation process, I try to reinstall Pr CS6. Thought I have a licence SN of CS6 which should be independent from that of CC, since I also prescribed a year licence of Pr CC. However, Adobe creative cloud told me I have exceeded the number of installed PC and had to disable one of them. It sounded very strange because I paid the money to both CS6 and CC prescription. What should I do because I have trouble in the future usage of CS6 ?