Suddenly I need to concat my sHQL instead of using setParameter??

Hello guys!

I ran into something strange yesterday that I have not solved in a pleasant way.

Some code that used to work stopped working.

As you see below I have comment-away the lines that used to work, and replacet it with one ugly concat row.

Then it worked, but of course I can not understand way and I do not like it.

public Payment getPaymentForReferens(final String referens) throws PaymentNotFoundException
{
 
  //final Query tPaymentQuery = em.createQuery("SELECT b FROM Payment b WHERE b.referens = :referens");
  //tPaymentQuery.setParameter("referens", referens);
 
  final Query tPaymentQuery = em.createQuery("SELECT b FROM Payment b WHERE b.referens = " + referens);
 
  Payment payment = null;
  final List<?> results = tPaymentQuery.getResultList();
  if(!results.isEmpty()) {
  payment = (Payment)results.get(0);
  }

  if(payment == null) {
  throw new PaymentNotFoundException(PaymentNotFoundException.PAYMENT_WITH_THIS_REFERENS_CAN_NOT_BE_FOUND + referens);
  }

  return payment;

}

All suggestions, comments and ideas what might have gone wrong is most welcome! 

The field/column in the database for 'referens' is char(36) in a Oracle.

Best regards
Fredrik