Keyboard isn't responsive after unlock OS-X (Mavericks) using AppleScript - objective-c

Question

I'm using AppleScript to lock the Mac from an external device (trigger) and unlock it from this same device.
Locking works great but when unlock my Mac keyboard and pads becomes unresponsive. Weird thing is when I move mousse after locking and get the password login if I enter the password the unlock makes keyboard responsive and only then.
Is it some kind of security settings I'm not aware of? How could I solve it?
Here is the script I'm using:
Lock:
tell application "System Events"
tell security preferences
set require password to wake to true
end tell
end tell
activate application "ScreenSaverEngine"
Unlock:
tell application "System Events"
tell security preferences
set require password to wake to false
end tell
end tell
tell application "ScreenSaverEngine" to quit
Please help I'm desperate. Also if you have another method you know to lock/unlock my Mac using code I would love to try it out!
Thanks!
UPDATE: To be clear when removing the password setting code (require password) the issue doesn't appear.
Meaning removing those 3 lines:
tell security preferences
set require password to wake to true
end tell
Doesn't have this issue, this is why I think it could be some security thing I'm not aware of.
UPDATE (26 Dec 2013): I didn't find any solution and bounty finished so what I'm doing is inserting my password using ActionScript (maybe this could help others having same issue). If you do have another solution I would love to know.

Answer 1

Try below for locking the screen, I am using the same and no issues while locking or unlocking. Hope this helps.
try
tell application "System Events"
set the process_flag to (exists process "ScreenSaverEngine")
end tell
if the process_flag is true then
ignoring application responses
tell application "System Events" to quit
end ignoring
else
set the target_app to ((path to "dlib" from system domain as string) & "Frameworks:ScreenSaver.framework:Versions:A:Resources:ScreenSaverEngine.app") as alias
tell application (target_app as string) to launch
end if
end try

Answer 2

Later today I'll be able to do more testing on a Mavericks machine. In the meantime, I have a little theory -- have you tested this with other screen savers "active"? I say this because I do have a couple of screen savers that are a little buggy, and I know that at least one of them needs an update for Mavericks. Which one are you using?
[UPDATE:] I did get on Mavericks and did not see the problems you described, or at least problems of that severity. I did get a little weirdness, though, possibly having to do with timing. What if you structure your script like this? For me, it covers for errors like "connection invalid" (I admit this is a little 'dangerous'; it might be good to put an upper limit of how many times it 'try's the activate by putting a counter in there):
tell application "System Events"
tell security preferences
set require password to wake to false
end tell
end tell
set connectionValid to false
repeat until connectionValid
try
activate application "ScreenSaverEngine"
set connectionValid to true
on error e
end try
end repeat