URGENTE - Tratamento de Valores!!

eu fiz assim e deu certo. coloque um Edit1, e um Button1

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;

type
TForm1 = class(TForm)
Edit1: TEdit;
Button1: TButton;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
Try
if (StrToFloat(Edit1.Text) < 0.00) or (StrToFloat(Edit1.Text) > 10.00) then begin
MessageDlg(´Digite um valor entre 0.00 e 10.00.´, mtError, [mbOK], 0);
exit;
end;
except
MessageDlg(´Digite um valor entre 0.00 e 10.00.´, mtError, [mbOK], 0);
end;
end;

end.