[plt-scheme] stumped with parser-tools

Good day all. I'm trying to learn parser-tools, as a 
stronger-than-regexps tool for general parsing needs.

http://paste.lisp.org/display/64069 shows a very simple grammar which is 
supposed to successfully parse "test", but fails with the error shown. I 
started from examples/calc.ss and have stared at all the examples, but 
can't see the reason for this error. Any insight welcome!