By default, Backtrace stores its log files in the Backtrace subfolder of the Enterprise Vault Reports folder. if you have everything configured correctly, it's possible that it's not detecting the error. also, in case you have multiple EV servers, make sure you set this on the actual EV server where you have the error.

looks like you have a typo in the registry path. it should be:

HKEY_LOCAL_MACHINE
\SOFTWARE
\Wow6432Node
\KVS
\Enterprise Vault
\Backtrace

make sure you have the right registry key types for each parameter such as string, dword, etc. backtrace is well documented in Utilities.pdf which comes with your EV install media. and just to make sure, the ones where you dont specify anything dont actually say "<blank>" do they? you dont have to have those keys if you want the defaults.

this should help too:

Enterprise Vault Event 8390 Errors - Troubleshooting Digest

• Article: HOWTO83884
• Updated: December 8, 2014
• Article URL: http://www.symantec.com/docs/HOWTO83884

Looks to be correct. I have seen where the Backtrace simply does not capture the event.

Does the event occur randomly; or is there any type of pattern? If so you can try running a dtrace via the Command Prompt and even use the pause command to try and time it if you will not be available to start the dtrace yourself.

Use the Event Logs to help you decide which services to capture, such as DirectoryService and so forth.

See page 50 of the Utilities Guide: https://support.symantec.com/en_US/article.DOC6040.html

Have you tried running with VSA account?
 

Thanks guys.  It's now working.  I think dtrace was open under another account and you can't run both at the same time I read somewhere, so kicked him off and away I go.  Thanks again.

that's correct. dtrace overrides backtrace.