PowerShell Script does not return XML result to sensor

I have the following PowerShell Script to check on a Horizon View Connection Server:

#
# Retrieve status of VMware Horizon Connection Servers
#

# set some parameters with default values
param (
    [string]$HVServer="server",
    [string]$HVUser="user",
    [string]$HVPass="password",
    [string]$HVFilter="*"
)

# if no $HVServer specified, don't do anything
if ($HVServer -ne "")
{
    #import necessary modules
    Import-Module VMware.VimAutomation.Core
    Import-Module VMware.VimAutomation.HorizonView
    
    # if no user/pass specified via parameters, prompt for user/pass, else use the parameters
    if ($HVUser -eq "" -or $HVPass -eq "") { $con = Connect-HVServer -Server $HVServer  }
    else { $con = Connect-HVServer -Server $HVServer -User $HVUser -Password $HVPass }
    
    # connect to the Horizon View API
    $viewAPI = $con.ExtensionData.ConnectionServerHealth.ConnectionserverHealth_List()
    
    # Start XML output for PRTG
    write-host "<prtg>"
    # loop through all connection servers
    foreach($cs in $viewAPI)
    {
        # check if Name matches filter specified
        if ($cs.Name -like $HVFilter)
        {
            # Get Connection Server status
            write-host "  <result>"
            write-host "    <channel>$($cs.Name) STATUS</channel>"
            if ($cs.Status -eq "OK") {write-host "    <value>1</value>"} else { write-host "    <value>2</value>"}
            write-host "    <unit>Custom</unit>"
            write-host "    <ValueLookup>prtg.standardlookups.yesno.stateyesok</ValueLookup>"
            write-host "  </result>"

            # Get Connection Server current connections
            write-host "  <result>"
            write-host "    <channel>$($cs.Name) # Connections</channel>"
            write-host "    <value>$($cs.ConnectionData.NumConnections)</value>"
            write-host "    <unit>Count</unit>"
            write-host "  </result>"

            # Get Connection Server current Composer connections
            write-host "  <result>"
            write-host "    <channel>$($cs.Name) # Composer Connections</channel>"
            write-host "    <value>$($cs.ConnectionData.NumViewComposerConnections)</value>"
            write-host "    <unit>Count</unit>"
            write-host "  </result>"

            # Get Connection Server tunneled connections
            write-host "  <result>"
            write-host "    <channel>$($cs.Name) # Tunneled Connections</channel>"
            write-host "    <value>$($cs.ConnectionData.NumTunneledSessions)</value>"
            write-host "    <unit>Count</unit>"
            write-host "  </result>"

            # Get Connection Server PCoIP Secure Gateway connections
            write-host "  <result>"
            write-host "    <channel>$($cs.Name) # PSG Connections</channel>"
            write-host "    <value>$($cs.ConnectionData.NumPSGSessions)</value>"
            write-host "    <unit>Count</unit>"
            write-host "  </result>"
        }
    }
    # close XML for PRTG output
    write-host "</prtg>"
    
    # disconnect from our connection server
    $con | Disconnect-HVServer -Force -Confirm:$false
}
exit 0

I get the following result when I run the script on the probe:

<prtg>
  <result>
    <channel>VIEWCON-201 STATUS</channel>
    <value>1</value>
    <unit>Custom</unit>
    <ValueLookup>prtg.standardlookups.yesno.stateyesok</ValueLookup>
  </result>
  <result>
    <channel>VIEWCON-201 # Connections</channel>
    <value>18</value>
    <unit>Count</unit>
  </result>
  <result>
    <channel>VIEWCON-201 # Composer Connections</channel>
    <value>0</value>
    <unit>Count</unit>
  </result>
  <result>
    <channel>VIEWCON-201 # Tunneled Connections</channel>
    <value>0</value>
    <unit>Count</unit>
  </result>
  <result>
    <channel>VIEWCON-201 # PSG Connections</channel>
    <value>0</value>
    <unit>Count</unit>
  </result>
  <result>
    <channel>VIEWCON-202 STATUS</channel>
    <value>1</value>
    <unit>Custom</unit>
    <ValueLookup>prtg.standardlookups.yesno.stateyesok</ValueLookup>
  </result>
  <result>
    <channel>VIEWCON-202 # Connections</channel>
    <value>23</value>
    <unit>Count</unit>
  </result>
  <result>
    <channel>VIEWCON-202 # Composer Connections</channel>
    <value>0</value>
    <unit>Count</unit>
  </result>
  <result>
    <channel>VIEWCON-202 # Tunneled Connections</channel>
    <value>0</value>
    <unit>Count</unit>
  </result>
  <result>
    <channel>VIEWCON-202 # PSG Connections</channel>
    <value>0</value>
    <unit>Count</unit>
  </result>
</prtg>

I created a new sensor (EXE/Script Advanced Sensor) and enabled "Store result in case of error".

If I look in the "result of sensor 12345.txt" file it just has one Line:

NUL NUL NUL NUL ... etc.

The file "result of sensor 12345.Data.txt contains the following:

Data['linuxloginpassword'].asString := '***';
Data['notonpod'].asString := '0';
Data['fastcount'].asString := '0';
Data['lastmsg'].asString := '#Y2 Junk after document element </prtg> @#O231[No mapping for the Unicode character exists in the target multi-byte code page]';
Data['resultfile'].asString := 'Result of Sensor 17412.txt';
Data['windowsloginusername'].asString := 'ruladmin';
Data['hostv6'].asString := '::1';
Data['exefile'].asString := 'ConnServerStatus.ps1';
Data['lastuptime'].asString := '0';
Data['writeresult'].asString := '2';
Data['blockedsens'].asString := '';
Data['reqmsginterval'].asString := '60';
Data['windowslogindomain'].asString := 'rul.gmbh';
Data['tlsexplicit_imap'].asString := '';
Data['channelnames'].asString := '';
Data['tlsexplicit_default'].asString := '';
Data['canlinux'].asString := '0';
Data['isexesensor'].asString := '1';
Data['windowsloginpassword'].asString := '***';
Data['environment'].asString := '';
Data['mutexname'].asString := '';
Data['channelinfos'].asString := '{}';
Data['uptimecount'].asString := '0';
Data['vmwareparams'].asString := '1';
Data['reboot'].asString := '44698.8894467593';
Data['usednstime'].asString := '0';
Data['newpowershell'].asString := '0';
Data['linuxlogindomain'].asString := '';
Data['exeparamshash'].asString := 'da39a3ee5e6b4b0d3255bfef95601890afd80709';
Data['tlsexplicit_port'].asString := '';
Data['monitorchange'].asString := '';
Data['inerror'].asString := '1';
Data['sensorid'].asString := '17412';
Data['ipversion'].asString := '0';
Data['tlsexplicit_smtp'].asString := '';
Data['host'].asString := '127.0.0.1';
Data['usewindowsauthentication'].asString := '0';
Data['simulate'].asString := '0';
Data['tlsexplicit_ftp'].asString := '';
Data['timeout'].asString := '120';
Data['exeparams'].asString := '';
Data['momopersistent'].asString := '';
Data['tlsexplicit_pop3'].asString := '';

I already googled a lot of possible solutions. So far I did not get this to work.

Any help would be appreciated