I got this error when I went through this process for the first time too. I don't know if this was the problem, but the last thing I did before I got it all to work for me was to install the "WWDR intermediate certificate". I found this by basically just clicking through the program portal (after spending about an hour just repeatedly uninstalling and re-installing all my certificates, because that was the only other advice I could find on this particular message). At the bottom of the certificates page, it says " *If you do not have the WWDR intermediate certificate installed, click here to download now. " Click on that, and I think it has you download the certificate, which I believe you double click to install. If you've already got the WWDR certificate installed, I have no idea, sorry! Good luck!