c# RPC server error when query for active username

Question

I have a function that connect to a remote computer using WMI. When I launch it with administrator privileges, the system says RPC server error.

I have the same kind of script in Powershell, it works correctly, no RPC server error (so WMI is working on the network, firewall isn't blocking it. I only found that kind of answer on the internet), and other softwares written in c# in the company are working correctly with those computers (the developer is no longer working for the company and I can't get my hand on the source code )

The same issue occurs whether I use the name of the computer or its IP adress.

static public string GetUsername(string computer)
    {

        string username = string.Empty;
        ManagementScope scope = new ManagementScope("\\\\computer\\root\\cimv2");
        //scope.Connect(); If I activate this line, the error occurs on this line
        string queryString = "select LogonId from win32_logonsession where logontype = 2";
        ManagementObjectSearcher query = new ManagementObjectSearcher(scope, new SelectQuery(queryString));
        foreach (ManagementObject mo in query.Get()) //if scope.connect(); is not activated, it's blocking on this line
        {
            username = mo["LogonId"].ToString();

        }



        return username;
    }

I tried to run my software from the Visual Studio or directly from the .exe (using administrator). I also tried an impersonation as a workstation admin programatically, but the problem is still there.

Thank you in advance for your kind help.

EDIT :

I already tried the solution with connectionOptions like this :

options.Username = "YOUR USERNAME";
options.Password = "YOUR PASSWORD";
options.Authority = "ntlmdomain:YOURDOMAIN";

and like this :

options.Username = "YOUR USERNAME";
options.Password = "YOUR PASSWORD";
options.Authority = "Kerberos:YOURDOMAIN";

and added the impersionation options

   options.Impersonation = ImpersonationLevel.Impersonate;
   options.EnablePrivileges = true;

Still not working.

Answer 1

Have you tried setting a username and password for the managmentscope like this?

static public string GetUsername(string computer)
{
    string username = string.Empty;
    ConnectionOptions options = new ConnectionOptions();
    options.Username = "YOUR USERNAME";
    options.Password = "YOUR PASSWORD";
    options.Authority = "ntlmdomain:YOURDOMAIN";
    ManagementScope scope = new ManagementScope("\\\\computer\\root\\cimv2",options);
    //scope.Connect(); If I activate this line, the error occurs on this line
    string queryString = "select LogonId from win32_logonsession where logontype = 2";
    ManagementObjectSearcher query = new ManagementObjectSearcher(scope, new SelectQuery(queryString));
    foreach (ManagementObject mo in query.Get()) //if scope.connect(); is not activated, it's blocking on this line
    {
        username = mo["LogonId"].ToString();
    }
    return username;
}

For more information have a look at the MSDN page for ManagementScope here And for the ConnectionOptions here.