\cS is not a valid color code, and is probably what's throwing the syntax error. A hint for the future: The error context doesn't show you EXACTLY where the error is, it shows you when the parser REALIZED there was an error. Usually you'll need to look at the double-pounded area or somewhere a little before it, but in very rare cases the true problem can be lines before the line it decides to notate, and may not even be visible in the error context dump.