CS6 upgrade will not accept my CS5.5 Serial number

Hello, I installed my previously purchased CS5.5 onto a new 64 bit laptop with Win 8.1 (I had previously tried to install the CS5.5 on a 32 bit machine and decided to uninstall a couple years ago so i did not really use it).  I then purchased and downloaded the CS6 Upgrade. When i start the set up of CS6 it accepts the CS6 serial number but then it does not accept the CS5.5 serial number by stating it is not a qualifying product.  Does anyone please know how i get by this to do the upgrade?  Thanks.