can't send WM_KEYDOWN correctly?

[sidooh]

Hi,everyone!

I'm tring to write a program to send key press message to other program(such as notepad).I mean if I press "M" in my program,this "M" will append to the notepad text entry.

here is my code:
hwnd = FindWindow(NULL,"Untitled - Notepad");
if(hwnd!=0){
char buffer[100] = "";
GetWindowText(hwnd,buffer,50);
MoveWindow(hwnd,0,0,500,500,TRUE);
SendMessage(hwnd,WM_KEYDOWN,VK_NUMPAD0,0);
SendMessage(hwnd,WM_KEYUP,VK_NUMPAD0,0);
printf("%d\n%s\n",hwnd,buffer);

}else{
printf("%d\n",hwnd);
printf("failure\n");
}


After running this program,the MoveWidnow() function worked,but there isn't any character in notepad text entry...
What should I do to solve this problem?
Any suggestion is appreciated!