"Symbol undefined" on interface with public getter and package setter

[TSalm]

Hello,

When I compile the code below, I've got the following error :
  OPTLINK (R) for Win32  Release 8.00.1
  Copyright (C) Digital Mars 1989-2004  All rights reserved.
  private_method_in_interface_file3.obj(private_method_in_interface_file3)
   Error 42: Symbol Undefined  
_D33private_method_in_interface_file31I4funcMFiZv
  --- errorlevel 1


/* ----- CODE ------ */
interface I
{
    int func() ;
    package void func(int);
}

class A:I
{
   int i;

   package  void func(int i)
   { this.i = i; }

   int func()
   { return i; }
}

void main()
{

   I a = new A ;
   a.func = 10 ;
   Stdout(a.func).newline ;

}
/* --- END CODE ---- */


Thanks in advance for your help,
TSalm