Powershell Issue "You cannot call a method on a null-valued expression" Extended Attribute

Hi All,

I need some help with this. I am trying to capture the Site Name via API (don't ask me why I have my reasons) Ofcourse with a bash shell no problems but as we do have some windows systems I would like to have it done for those computers as well. So I created a powershell script which should do the trick.

When I run this script on the windows machine I have a result like:
<result>sitename</result>

When I run this via the recon I get : "You cannot call a method on a null-valued expression"

When I google this error I get results get a variable is not set.. Just can't see which one..

Any Ideas?

$computername = Get-WMIObject Win32_ComputerSystem | Select-Object -ExpandProperty name
$url = "https://jss.xxxx:8443/JSSResource/computers/name/$computername"
$username = "xxxx"
$password = "xxxxxx"
$webclient = New-Object System.Net.WebClient
$webclient.Credentials = New-Object System.Net.NetworkCredential($username, $password)
[xml]$webpage = $webclient.DownloadString($url)

$sitename = $webpage.SelectNodes("//computer/general/site")

$result = $sitename.OuterXml.Split('><')[8]

echo "<result>$result</result>"