MSI requires separator character for append or remove
The indicated object specifies an append or prepend installation action, but the separator character is empty. MSI cannot handle empty separator characters with append or prepend; instead, it will use the first or last character of the actual value as the separator character. This will probably cause problems.
Make sure that you specify a suitable separator character if you request append or prepend and are building an MSI installer. Alternatively, build an InstallMate installer instead.
InstallMate versus Windows Installer