System.Management.ManagementException: Invalid parameter

[Ravi L]

I have created a windows Service which invokes executables on remote machines, waits for it to complete and then proceeds to the next machine on the network.
The Account type for the windows Service is "Network Service". For monitoring if the process is completed on the remote machine, I am using ManagementEventWatcher class. I get the following error when I start the Management event watcher object.

System.Management.ManagementException: Invalid parameter
at System.Management.ManagementException.ThrowWithExt endedInfo(ManagementStatus errorCode)
at System.Management.ManagementEventWatcher.Start()

The code I am using is as follows:

Dim connection As New System.Management.ConnectionOptions
connection.Username = v_sUserName
connection.Password = v_sPassword
connection.EnablePrivileges = True

Dim oPath As New ManagementPath("\\" & v_sServerName & "\root\CIMV2")
Dim oScope As New System.Management.ManagementScope(oPath, connection)
oScope.Options.Impersonation = ImpersonationLevel.Impersonate
oScope.Connect()

Dim processClass = New System.Management.ManagementClass("Win32_Process")
processClass.Scope = oScope

Dim inParams = processClass.GetMethodParameters("Create")
inParams("CommandLine")="C:\Myfolder\myexe.exe"
Dim oOutParams As ManagementBaseObject = processClass.InvokeMethod("Create", inParams, Nothing)
Dim sWQLQry As String = "SELECT * FROM __InstanceOperationEvent " & _ "WITHIN 2 WHERE TargetInstance ISA 'Win32_Process' " & _
"AND TargetInstance.Name = '" & "MPSFileAuditSatellite.exe" & "'"

Dim oWatcher As ManagementEventWatcher = New ManagementEventWatcher(oScope, oWQL)
oWatcher.Start()'I presume the error is here.
'Logic to wait for the process to exit.

what is wrong in the scope?
It used to work earlier when the service was of type User. Does this depend on the service account type and does not work when using Network Service?

Thanks in advance.

[Ravi L]

I have an update on this. The exception occurs only when the Service account is of type NetWork Service. If it is a User type it works smooth.