Should be simple enough, but i cant get it to work. First time using API.

Im trying to send text to a Notepad window. Code is below:

---
winHwnd = FindWindow(vbNullString, "notepad.txt - Notepad")
If winHwnd <> 0 Then
msgbox "found"
SendMessage winHwnd, WM_SETTEXT, 0, "hello"
end if
---

It finds the proper window, hence I get "found" in a msgbox.
But it does not send the "hello" to the Notepad.

What am i doing wrong? Sample code would be appreciated. Thanx.