[antlr-interest] expecting "class", found 'class'

[clocKwize]

anyone know why this would happen, I totally new to antlr and I'm just 
playing, I have:

class_def        :    "class" IDENT ("extends" IDENT)? SEMI;

...

IDENT options {testLiterals=true;}
            : ('a'..'z' | 'A'..'Z') ('a'..'z'|'A'..'Z'|'_'| DIGIT)*;
           
protected
DIGIT            :    '0'..'9';

WS            :    (' ' | '\t' | '\n' | '\r') { _ttype = 
ANTLR_USE_NAMESPACE(antlr)Token::SKIP; };


in my test file i have: "class ClassName extends Moo;"



Thanks,


Mike