Repeating QRGroup Band when the expression is not changed?!?!?

hi
i had a problem with changing the expression at runtime, but mr.italo gomez
helped me with that (earlier at the listgroup). now i am changing the
expression at runtime via the following code :

procedure UpdateExpression(newstr : string);
var
  QREvResult: TQREvResult;
begin
  QREvResult.Kind := resString;
  QREvResult.strResult := newstr;
  frmRepDiary.QuickRep1.Functions.UpdateConstant('GrBreak',QREvResult);
end;

this works fine (many thanks to mr.gomez), but it repeats the GroupBand on
the first repetition of the expression?!?
can anybody help with this? Team B maybe?
thanks in advance!
Stefan