I am very new to programming in TrueUpdate 3.5

I need my client scrpt to use HTTP Authentication login before it can download the server script. During build time, I entered my user name and password.

In the client script, before:
if(Screen.Show("Connect to Server") == SR_SUCCESS) then
TrueUpdate.RunScript("Server Script");

I added this code:
"Dialog.Message("The userName is "..g_HTTPAuthUsername);"

But, when I run the client script, I get an Error:

"Client Script, Line 37: attempt to concatenate global g_HTTPAuthUsername (a nil value)"

How can I make the client script tell me what the value is?

Thank you,