Thanks for your quick response.
I double checked my code, I made mistake when paste code to the post, but not in my original code.
I tried your keys, it works for me either. I tried many different keys, all works but all keys under "HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/Updates", including several keys like:"HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/Updates/UpdateExeVolatile", no space in it; "HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/Updates/Windows Server 2003". I don't know why...I refreshed and didn't work. Apparently it's not related to the white space.