DLL怎么调用另一个DLL

DLL如何调用另一个DLL
library   Project1;

{   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
    SysUtils,Classes,Windows,   Messages,   Variants,   Graphics,   Controls,   Forms,
    Dialogs,   StdCtrls,IniFiles,Wcrypt2,   comObj,ComServ;

type
HS_FILEINFO=record
    dwFileID:integer;
end;
        procedure   _SignFile(var   szSourceFile,szSignatureFile,szDescription   :string);
        procedure   readusbkeyfile_HD;   //华大产品
        procedure   CleanAll;
        procedure   _Exit(msg   :string);
        function   EOF(hFile   :THANDLE;   BytesRead   :DWORD):boolean;

var
v1:string;
temp_path:string;
hSourceFile   :THANDLE;
hSourceFilex   :THANDLE;
function   HSFormat(hcard:pointer;FormatInfo:HS_FORMATINFO):DWORD;stdcall   ;   external   'HD_GPAPI.dll '   ;

{$R   *.res}

begin
end.


build的时候出错   Invalid   compiler   directive:   'EXTERNAL '  

有没有办法在编写DLL的时候调用其他的DLL文件，具体如何调用？


------解决方案--------------------
方法正确的~DLL就是这样的嘛~
放在VAR之前嘛~
------解决方案--------------------
仔細看看有沒有少什麽東西吧