PD8 activation code will not let me activate PD9 upgrade

Hi,
I recently installed the Yosemite OSX onto my MacBook Air. I have an activation code for PD8 and installed PD9, following the upgrade directions in KB http://kb.parallels.com/en/116989. I have managed to successfully install PD9 onto my system but I' am running into trouble with my PD8 activation code.
According to the documentation, I should be able to use my PD8 code to upgrade to PD9, but I'm running into this error message:
"This key cannot be used with Parallel Desktop Build 9.0.24251. For details, please click here (http://kb.parallels.com/en/111769/).