Shell – Use a script for a telnet session

I have a problem with my script. It seems my password is wrong.

#!/usr/bin/expect

set ip [lindex $argv 0]
spawn telnet $ip
set timeout 10
expect "Login:"
send "administrator\r"
expect "Password:"
send "123456"
send "\r"

It says, login incorrect. But it works, when i use cmd on Windows to telnet to my phone, it works with "administrator" and 123456 as password.
I don't know why in my script, I could not log on successfully.

I have to use this script to downgrade/upgrade my phones.