[racket] How to use parser-tools/yacc-to-scheme?

Hello.

I prepared a tiny-tiny file having this(test.l):

%{
%}
%%
a(b|c)*  { printf("OK\n"); }  /*Finding this pattern shows O.K.*/
. {printf("NG\n");}  /*. shows ELSE */
%%
/* Nothing */

And now, as the document of Parser Tools says, try runnning these command.

> (require parser-tools/yacc-to-scheme)
> (trans "./test.l")

It gives me something like an error:

<unsaved editor>:3:2: lexer: No match found in input starting with:

Did I misunderstand or do something wrong?

Thanks.
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