MBSDK-AddDeviceToScheduledTask return false

Hi,

I can’t add a computer to a scheduled task using the MBSDK.

This Powershell return false :

      $landeskService = New-WebServiceProxy -Uri  http://coresrv/MBSDKService/MsgSDK.asmx?WSDL -UseDefaultCredential

      $landeskService.AddDeviceToScheduledTask(170,"PCNAME")

And direct HTTP request  "http://core/MBSDKService/MsgSDK.asmx/AddDeviceToScheduledTask?taskId=170&deviceName=PCNAME"

return :

     <?xml version="1.0" encoding="UTF-8"?>

     <boolean xmlns="http://landesk.com/MBSDKService/MBSDK/">false</boolean>

Thanks