Your code worked successfully on my computer, as you posted it. All I added was the win64 regview setting. So it's not the code itself.

 Code:
$nul = setoption("WOW64AlternateRegView", "on")

$HKLMS='HKEY_LOCAL_MACHINE\SOFTWARE\'
;Disable Java Auto Update
$rc = WRITEVALUE($HKLMS + "JavaSoft\Java Update\Policy", "EnableJavaUpdate", "0", "REG_DWORD")