problema con dll
 

Hola como estan.
Teengo un problema al realizar una dll este es el codigo.

este es el programa

Código Delphi [-]
Código Delphi [-] 
unit Unit1;
interface
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;
type
  TForm1 = class(TForm)
    Label1: TLabel;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
var
  Form1: TForm1;
  function GetPCName(): Pchar;stdcall; external 'CPU.dll';
implementation
{$R *.dfm}
procedure TForm1.Button1Click(Sender: TObject);
var
c: pchar;
begin
c:=GetPCname();
label1.Caption :=c;
end;
end.

esta es la dll para obtener el nombre del pc.

Código Delphi [-]
library Código Delphi [-] 
CPU;
{ Important note about DLL memory management: ShareMem must be the
  first unit in your library's USES clause AND your project's (select
  Project-View Source) USES clause if your DLL exports any procedures or
  functions that pass strings as parameters or function results. This
  applies to all strings passed to and from your DLL--even those that
  are nested in records and classes. ShareMem is the interface unit to
  the BORLNDMM.DLL shared memory manager, which must be deployed along
  with your DLL. To avoid using BORLNDMM.DLL, pass string information
  using PChar or ShortString parameters. }
uses
  windows,
  SysUtils,
   classes;
{$R *.res}
function GetPCName(): Pchar;stdcall;
var
  PC: Pchar;
  Tam: Cardinal;
begin
  Tam := 100;
  Getmem(PC, Tam);
 GetComputerName(PC, Tam);
  Result := PC;
  FreeMem(PC);
end;
exports GetPCname;
begin
end

.

al ejecutar el programa me da error no me coge bien la dll o no la estoy haciendo bien
alguna idea.. gracias de antemano

leiste lo del sharemem q pone en los comentarios?