BarTender engine could not be started. Possible reasons are:

1) BarTender is not properly installed.
2) BarTender is not properly registered on the computer (e.g bartend.exe /register).
3) There are too many process instances of BarTender running. Stop a few bartend.exe instances and try again. Also see SDK Engine.Start method documentation for information about how to allow more BarTender processes to run on your computer by increasing your "non-interactive" shared desktop heap.
4) The user account does not have permission to run BarTender.