TidContext does not contain a member name Connection

This simple structure does not work in my code.

procedure Tform3.IdTCPServer1Execute(AContext: TIdContext);
var
   i: Integer;
begin
   for i := 1 to 15 do begin
     AContext.Connection.IOHandler.WriteLn(IntToStr(i));
     Sleep(1000);
   end;
   TidTCPConnection.Disconnect;
end;

The error is : TidContext does not contain a member name Connection.

I'm using INDY 10.

Can you help a Beginner ?

Thanks