菜菜的钩子问题


写好了DLL文件,可是在EXE中调用一点反应也没有,
implementation
Function SetHook:Boolean;stdcall ;  external 'Project2.dll';声明后,在调用的地方写sethook然后按下F12一点反应也没有,还有下面好几个问题,麻烦帮忙看看
library Project2;uses
  SysUtils,
  windows,
  Classes;
var
    OldHook:HHOOK;{$R *.res}
Function HookProc(nCode,wParam,lParam:Integer):Integer;stdcall;export;
begin
  //设置热键
  if (wParam=VK_F12) then messagebox(0,'1','1',MB_OK);
  Result:=CallNextHookEx(OldHook,nCode,wParam,lParam);
end;function UninstallHook: Boolean;stdcall; export;
begin
  Result := UnHookWindowsHookEx(OldHook);
end;
Function SetHook:Boolean;stdcall; export;
var
    Histance:Cardinal;
begin
  Histance:=0;    //这里该怎么初始化了呀?????
  OldHook:=SetWindowsHookEx(WH_KEYBOARD,@HookProc,Histance,0);
  Result:=True;
end;exports
SetHook;
-------------->UninstallHook怎么导出了呀,写在这就提示出错了
begin
end.