Free Audio FX 3 Pack

Hi all.
I did a search on this topic but could not find anything. If there is, I apologize for posting.
 
About a year ago, I downloaded the free version and installed it to run with SONAR 8.53 Studio. A few weeks ago, I needed Sonar 6 Studio for an old project to transfer onto 8.53. Lo and behold, I saw Soundstage, which did NOT come up in 8.53, whereas the other FX Pack 3's effects did come up. I went into FX 3's log file and saw the lines below:
 
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Could not Self-Register: C:\Program Files (x86)\Cakewalk Audio FX Pack 3\CWPlugin.dll
Self-Register: C:\Program Files (x86)\Cakewalk Audio FX Pack 3\soundstage.ax
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and then on to Cakewalk Store's site/My account to get FX Pack's serial number, and then back to the Registration page. Plugged it in and the Registration program invariably came back with "Invalid serial number".
 
However, when I plugged in 8.53's serial number, Registration took it (even though I clearly chose FX Pack 3 in the product field) and said "Thank you, your product has been registered", but it did NOT give me a registration number.
 
What's the remedy here? Anyone know?
 
Thank you, S.