Post an error report (Help menu) from within VemsTune (requires internet connection), then post the link here given to you by the program.
That way, we can see the configuration parameters, and it also tells us which firmware you're running, etc.
Suggestion: Install absolute latest VemsTune (not the stable version) and "update files manually" from the Preferences menu. Upgrade firmware to 1.2.23, and start fresh from there.