[DUG]: String vs Integer

[Richter Decorações Ltda]

Hi All I have a program that receives a partial date in a DBEdit control, but when i try to validate de entry, i get a error message. What am i doing wrong ?   procedure TForm1.DBEdit1Exit(Sender: TObject);   var     DD,MM,S : String;   begin     S := DBEdit1.Text;     DD := S[1] + S[2};     MM := S[3] + S[4];     if (DD < '1') or (DD > '31') or (MM < '1') or (MM > '12') then       begin         MessageDlg('Invalid Date. Try again !', mtWarning, [mbOk], 0);         DBEdit1.SetFocus;       end     else       Perform(WM_NEXTDLGCTL, 0, 0);   end;      TIA   Joao Alberto Licht Teixeira