RESUME and no error (ERR=104)

  The program either executes a RESUME statement outside  of  the  error
  handling  routine or calls a subprogram from the error handler and the
  subprogram executes an ON ERROR  GO  BACK  statement.   Check  program
  logic  to  make sure that the RESUME statement is executed only in the
  error handler, or remove the ON  ERROR  GO  BACK  statement  from  the
  subprogram.  This error cannot be trapped with a BASIC error handler.