用VB写dll，遇到的问题

搞一个窗口未获得焦点也能自动填写文本的辅助程序，碰到了模拟组合键无效的难题，比如Ctrl+A是全选文本，但一失去焦点就毫无反应，
  在网上找到一个VB模拟按键的方法，想做成dll调用，如下：
向未激活的窗口发送组合键，想用三个参数，第一个是窗口句柄hWnd，第二个是修饰键如Ctrl，第三个是普通按键如A。
带参数调用这个dll的相应命令即发送不同的组合键。

我不会VB，想简单拼凑一个应急，可无法编译，子程序或函数未定义。
Sub ZuHe1(hWnd As Integer)
  keybd_event VK_CONTROL, &H1D, 0, 0 ' 模拟按下SHIFT键，&H2A是VK_SHIFT的扫描码
  PostMessage hWndMsg, WM_KEYDOWN, VK_A, &H1E0001 ' 模拟按下 A 键，SHIFT+A产生一个大写A字符
  PostMessage hWndMsg, WM_KEYUP, VK_A, &HC01E0001 ' 模拟抬起 A 键
  keybd_event VK_CONTROL, &H1D, KEYEVENTF_KEYUP, 0 ' 模拟抬起 SHIFT 键
End Sub

Sub ZuHe2(hWnd As Integer)
  PostMessage hWndMsg, WM_SYSKEYDOWN, VK_F4, &H3E0001 Or &H20000000 ' 模拟按下 Alt+F4
  PostMessage hWndMsg, WM_SYSKEYUP, VK_F4, &HC03E0001 Or &H20000000 ' 模拟抬起 Alt+F4
End Sub

请高手帮忙补充成完整代码,先把手头的任务完成．

Private Declare Function PostMessage Lib "user32" Alias "PostMessageA" (ByVal Hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Private Const VK_CONTROL = &H11
Private Const WM_KEYDOWN = &H100
Private Const WM_KEYUP = &H101
Private Const KEYEVENTF_KEYUP = &H2
Private Const WM_SYSKEYDOWN = &H104
Private Const WM_SYSKEYUP = &H105

Private Declare Sub keybd_event Lib "user32" (ByVal bVk As Byte, ByVal bScan As Byte, ByVal dwFlags As Long, ByVal dwExtraInfo As Long)
Private Const KEYEVENTF_EXTENDEDKEY = &H1

Sub ZuHe1(Hwnd As Long)
  keybd_event VK_CONTROL, &H1D, 0, 0 ' 模拟按下Ctrl键，&H2A是VK_SHIFT的扫描码
  PostMessage Hwnd, WM_KEYDOWN, VK_A, &H1E0001 ' 模拟按下 A 键，SHIFT+A产生一个大写A字符
  PostMessage Hwnd, WM_KEYUP, VK_A, &HC01E0001 ' 模拟抬起 A 键
  keybd_event VK_CONTROL, &H1D, KEYEVENTF_KEYUP, 0 ' 模拟抬起 Ctrl 键
End Sub
Sub ZuHe2(hWndMsg As Integer)
  PostMessage hWndMsg, WM_SYSKEYDOWN, VK_F4, &H3E0001 Or &H20000000 ' 模拟按下 Alt+F4
  PostMessage hWndMsg, WM_SYSKEYUP, VK_F4, &HC03E0001 Or &H20000000 ' 模拟抬起 Alt+F4
End Sub
改了，能编译，但没用。怎么传递参数进来呢？