Failed to connect to the SQL database 'SSODB' on SQL Server

Last week I was with a customer that had problems to configure a  BizTalk Server 2009 development environment. They got the following error when they tried to enable Enterprise Single Sign-On on that environment: "Failed to connect to the SQL database 'SSODB' on SQL Server"

I reviewed the Event Viewer and I found the following error message: "Login Failed – Error: 18456, Severity: 14, State: 38 – Reason: Failed to Open the Explicitly Specified Database". Fortunately, I remembered that I had the same problem some years ago... for some reason, the the assembly used by Enterprise Single Sign-On to access SQL Server (SSOSQL.dll)  fail to load and it is necessary re-register the assembly with the "regasm" tool. So...

• I opened a Command Window as administrator.
• I went to: "C:\Windows\Microsoft.NET\Framework\v4.0.30319\"
• And I executed the following command: 

regasm.exe" "C:\Program Files\Common Files\Enterprise Single Sign-On\ssosql.dll" 

Finally, I started the BizTalk Server configuration process again and when I enabled Enterprise Single Sign-On everything worked fine.