Skús to takto: poznamka <> '%kr%', alebo si to ošetri v udalosti OnFilterRecord:

ADODatasetFilterRecord(...); 
var
   str: string;
begin
   str := uppercase(ADODataset.FieldByName('poznamka').AsString);
   if pos('kr', str) > 1 then
      Accept := False
   else
      Accept := True;
end;