The following code was happily and successfully selecting data for just the chosen operator, now its gone back to selecting all operators (or damn near all). I don't know what I've done to make it change its mind.

Any ideas?

SELECT ET.Operator, ET.Route, ET.Class, ET.Date, ET.RorF, op.Desc as OpDesc, RF1.ServType, ;
  IIF( ET.Route == ET.Mcl_Rte, "    ", ET.Mcl_Rte) as ContrNum, ;
  SUM( IIF( BETWEEN( ET.date, ldStartCurr, ldEndCurr), ET.Number, 0000000)) AS CurrPass, ;
  SUM( IIF( BETWEEN( ET.date, ldStartPrev, ldEndPrev), ET.Number, 0000000)) AS PrevPass ;
  FROM ETMData ET ;
    JOIN Operator op ;
	On ET.Operator  == op.Code ;
    JOIN RF1 ;
	On  ET.Operator == RF1.Operator ;
	and ET.Route    == RF1.ERoute ;
  WHERE op.Code	       == lnOpCode ;
  And	(   ET.date BETWEEN ldStartCurr and ldEndCurr ;
  	 OR ET.date BETWEEN ldStartPrev and ldEndPrev) ;
  GROUP BY ET.Mcl_Rte, ET.Operator, ET.Route, ET.Class ;
  ORDER BY ET.Operator, ET.Route, ET.Class ;
  INTO CURSOR csrETMPassengers NOFILTER