Antlr4 semantic predicates to parse a date

Question

I started here and here to come up with the following start, but I am getting the error: "Problems calling org.antlr.v4.gui.TestRig.main(args)". If someone could tell me where I am messing up I would appreciate it

Form to parse : dd/mm/yyyy

• dd must be between 01 and 31

• mm must be between 01 and 12

  lexer grammar dates;
  
  fragment DIGIT: [0123456789];
  
  DATE : DAY ('/'MONTH+) ('/'YEAR+)
      {System.out.println(getText() + " is a valid Date");};
  
  DAY : TWODIGIT
      {Integer.parseInt(getText()) >= 1 && Integer.parseInt(getText()) <= 31}?;
  MONTH : TWODIGIT
      {Integer.parseInt(getText()) >= 1 && Integer.parseInt(getText()) <= 12}?;
  YEAR : FOURDIGIT
      {Integer.parseInt(getText()) >= 2000 && Integer.parseInt(getText()) <= 2100}?;
  
  TWODIGIT : DIGIT DIGIT;
  FOURDIGIT : DIGIT DIGIT DIGIT DIGIT;
  WS: [\r\n\t]+{skip();};
  

Does the problem have to do with the fact that according to how things are currently, all months are days?

Thanks!