subclassing procedure

Hello.

After reading a bit about hooks (Richter, etc.), I am trying to implement
a program that will subclass the procedure belonging to a dialog of another
application (on a Win95 or NT system).

Unfortunately, I cannot make it work.
Can you please help me find what's wrong?

What I'm trying to do is:

In my EXE file (console app):
------------------------------
1) Start the target application using CreateProcess()

2) Load a DLL with the hook using LoadLibrary() and
   get  the hooking procedure address using GetProcAddress().

3) Call the hooking procedure with the target app's thread ID as a parameter.

4) Wait for the target app to exit (using WaitForSingleObject())

5) Remove the hook, free the DLL, cleanup and exit.

No message loop or anything fancy...


In my DLL:
------------
1) In the DllMain() - Save the DLL hInstance.

2) In the hooking proc - call:
   hHook = SetWindowsHookEx(WH_GETMESSAGE, GetMsgProc, hinstDll, dwThreadId);
   passing the saved DLL hInstance and the target app's thread ID
   (from the EXE step #3).

   [problem #1]

3) In the Hook - do something like:

   if (code == HC_ACTION && wParam == PM_REMOVE &&
       ((MSG*)lParam)->message == WM_INITDIALOG &&
       MyCompareDialog(((MSG*)lParam)->hwnd))
   {
       oldDlgProc = SubclassDialog(((MSG*)lParam)->hwnd, MyDlgProc);
   }
   return CallNextHookEx(hHook, code, wParam, lParam);

   [problem #2]

4) In MyCompareDialog() - get the dialog's title using GetWindowText()
   and compare it to the title of the dialog I wish to subclass.

5) In MyDlgProc() - do something like:

   switch (message)
   {
       case WM_COMMAND:
           switch GET_WM_COMMAND_ID(wParam, lParam)
           {
               case 57670: // A button identifier, found with Spy++
                   MessageBox(NULL, "Gotcha!", "Info", MB_ICONINFORMATION);
                   return TRUE; // Message was processed
           }
   }
   // Call previous dialog procedure
   return CallWindowProc((WNDPROC)oldDlgProc, hWnd, message, wParam, lParam);

Now the problems:

Problem #1:
        The call to SetWindowsHookEx() sometimes fails with error 87
        (invalid parameter), but if I put a breakpoint on the line and
        then continue, it seems to work OK.  Huh?

Problem #2:
        The hook does not seem to catch WM_INITDIALOG.
        In fact, the first message it gets is WM_MOUSEMOVE (0x200).