EXE Custom Sensor using Powershell

I have stumped Support with this one.

I want to create an EXE Custom Sensor to run a WMI command against a remote server that returns back the number of patches applied in the last X number of days. I have set the Parameters to %host, see it as $args[0] in my powershell script but cannot use it in -computername field for it to return any value. This works fine from command line and passing in the argument. From PRTG, it only returns the value of $srv.

$srv = $($args[0])
$ans = gwmi win32_quickfixengineering -cn $srv
$output = "$srv $ans"
$output | out-file "c:\windows\temp\PRTG.out" -append

exe powershell wmi