I am trying to write text into a windows edit control using python. it seems to write to every control i try except the edit box not sure if this is a security measure or not. here is my code any help will be greatly apprciated.

import os,sys,subprocess,time
from subprocess import *
from os import *
from ctypes import *
from ctypes.wintypes import *

PROCESS_ALL_ACCESS =     ( 0x000F0000 | 0x00100000 | 0xFFF )
kernel32 = windll.kernel32
pid      = sys.argv[1]

h_process = kernel32.OpenProcess( PROCESS_ALL_ACCESS, False, int(pid) )

if not h_process:
    print "[*] Couldn't acquire a handle to PID: %s" % pid

user32 = windll.user32
# parent window
window_handle = windll.user32.FindWindowA(None, "Windows App")

if not window_handle:
    print "[*] cant find window"

# 1 is the control id of the edit box child window
#below line has no effect on the control for some reason??
windll.user32.SetDlgItemTextA(window_handle, 1, "bla")

# 2 is the control id of a button
# this line works ? not sure whats going on
windll.user32.SetDlgItemTextA(window_handle, 2, "bla")