Dimension Pro Won't Register [SOLVED]

First of all, I do own and have Rapture, Rapture Pro, Dimension Pro, and Dimension Pro 1.5 (x2) products in my product area.
 
However, while the Rapture products load fine in SPLAT latest version, Dimension Pro does not.  I get a "Complete Registration: D-Pro" dialogue box.  It is showing the Serial Number correctly for one of my products but the Registration Code listed in my account for that SN does not work.  I tried the other product RC but it doesn't work either (didn't expect it to but tried).
 
I know there's no need to load DP1.5 alone since I have RapturePro but it bugs me since it's a legit product.  Any thoughts?
 
EDIT: to add that this is installed via CCC with everything showing up to date.  Also, the product showing in SPLAT which won't register is a different version (one of two DP1.5 products listed in my account) than shows in CCC which shows the 2nd of the two products listed in my account.  Huh?

If you installed the DPro packages under RPro all the programs and samples from DRpo would be in the RPro sample and program libraries and the samples and programs installed by DPro would be rendundant. AFAIK, the only programs that do not play properly in RPro are the VB3 programs which came with DPro Expansion Pack 1. These programs have a lot of special features tied to the DPro UI which RPro does not replicate.
 
FWIW, to register DPro after manually installing it, run the stand alone version as administrator and use the latest activation codes from your account.

Nope, installing manually fails to install.  While the download page from my account shows the same product SN & RC, it does not accept any of the RCs listed including the one shown on the download page.

Okay, I took a look through the registry but didn't change anything.  I'll try that now.

I didn't find the dp directory under HKEY_LOCAL_MACHINE\SOFTWARE\Cakewalk Music Software but did find it under HKEY_USERS\HKEY_USERS\S-1-5-21-2544713292-1054752897-3434999625-1001\SOFTWARE\Cakewalk Music Software
 
Okay to remove it from there?

Thanks scook.  I used your link (couldn't remember where to find that!) and followed those instructions.  It let me use one of my other SNs and seemed to load fine.  There was no stand-alone version so opened SPLAT and tried to load it but got the same dialogue box.  Again, none of the RCs worked including the one associated with that SN.
 

Success!  Yes, I ran the standalone DP executable from that location as administrator.  The registration dialogue came up but this time it accepted the correct RC.  It now loads fine in SPLAT.  It did not change the CCC listing which still shows a different SN.
 
Thanks so much scook!