Auto login to Windows using SEND commands & Dell KACE

We have Dell KACE managing all of our machines, which allows us to run scripts, programs, etc while the machine is logged off. I figured I would make a simple "auto login" script that would log the machine into Windows while sitting at the domain username and password field. However, it's not working. I'm new to AutoIT, but have made some basic scripts that work so far and this one seems pretty straight forward. I tell my KACE appliance to run the exe I compiled on the machine, but nothing happens (even with the blinking input cursor in the username field). While in Windows/notepad, it works - just not at the login screen. Is this some limitation in regards to AutoIT scripts?

Sleep(2000)
Send("pctech")
Send("{TAB}")
Send("XXX")
Send("{ENTER}")

Any ideas? Using our KACE appliance, it should run - so I'm not sure if it's KACE, or AutoIT.