// Note: Must first change primary index of DBDEMOS orders table to CustNo;OrderNo

procedure TForm1.Button1Click(Sender: TObject);
begin
   Customer.Filter:='State='+QuotedStr('FL');
   Customer.Filtered:=True;
end;

// This button click causes the problem

procedure TForm1.Button2Click(Sender: TObject);
begin
   Orders.Close;
   Customer.Filter:='';
   Customer.Filtered :=false;
   Orders.Open;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
   Orders.IndexFieldNames :='CustNo;OrderNo';
   Orders.MasterSource:=CustomersSource;
   Orders.MasterFields:='CustNo';
   Orders.Filter :='Freight=0';
   Orders.Filtered :=true;
end;