Need help with AutoIT script created to handle browser authentication pop up

Question

I have written below AutoIT script to handle the browser auth window as below.

I have parameterized script to get the uname & pwd from command line. With this parameterized script during execution it enters the values into the uname & pwd fields and hopefully clicks Ok as well but do not logs in actually & throws back the auth window like when we enter something wrong though all details are correct.

I tried hard-coding the login info into script & tried running then its working as expected.

I am not able to understand whats going wrong with the parameterized one. Can anyone help with it?

Below is the AutoIt code :

#include <MsgBoxConstants.au3>
$user=$CmdLine[1]
Sleep(5000)

if WinExists("Authentication Required") Then
    WinActivate("Authentication Required")
    Sleep(2000)
    ControlSend("Authentication Required", "", "", $user&"{TAB}")
    ;ControlSend("Authentication Required", "", "", "Disconnect_123{TAB}")
    Sleep(5000)
    ControlSend("Authentication Required", "", "", $user&"{TAB}")
    ;ControlSend("Authentication Required", "", "", "Disconnect_123{TAB}")
    Sleep(5000)
    ControlSend("Authentication Required", "", "", "{ENTER}")
;ControlClick("Authentication Required", "OK", "controlID", "left", 1")
EndIf