AppleScript: keystroke 125 (down key) on Mavericks - applescript

Question

In Mac Lion: choose lock screen in lockscreen icon (Keychain Access -> Preferences --> General -> Show keychain ...), it will in screen saver mode.
In mavericks: when lock screen by above steps, it is NOT in screen saver mode. So we can not control it. I don't know why???
Then in locked screen, I tranfer event to press down key On MAVERICKS (It's OK on Mac Lion), but it seems not know about that:
on run
tell application "/System/Library/Frameworks/ScreenSaver.framework/Versions/A/Resources/ScreenSaverEngine.app" to quit
tell application "System Events" to key code 125
delay 1
tell application "System Events" to keystroke "password"
delay 1
tell application "System Events" to keystroke return
delay 5
end run
Excute above script by:
NSString *source = [NSString stringWithFormat:kAppleScriptUnlockWithPassword ,password];
// Create unlock script with password
NSAppleScript* appleScript = [[NSAppleScript alloc] initWithSource:source];
NSDictionary * errDic = nil;
// Execute script
[screenState removeAllObjects];
[appleScript executeAndReturnError:&errDic];
NSLog(#"%#", errDic);
It returns:
{
NSAppleScriptErrorAppName = "System Events";
NSAppleScriptErrorBriefMessage = "Can\U2019t make {1, \"\"} into type text.";
NSAppleScriptErrorMessage = "System Events got an error: Can\U2019t make {1, \"\"} into type text.";
NSAppleScriptErrorNumber = "-1700";
NSAppleScriptErrorRange = "NSRange: {92, 20}";
}
Do you have any idea about it?
Please help me.
Thanks

Answer 1

keystroke 125 inserts 125 as text. Try using key code instead:
quit application "ScreenSaverEngine"
tell application "System Events"
key code 125
delay 1
keystroke "password" & return
end tell