Change adapter setting from dynamic to static

问题:

I've seen a lot of code that allows me to set the IP address of a local workstation, but it only works if the workstation already has a static IP address. I need to change the adapter settings from obtaining an IP address automatically to using a static IP I give it.

The code I'm using now is below. It fails on the first if statement for every objMO. I know at least one adapter has IPv4 enbled (I can see it in the Network and Sharing Center), but, like I said, it is set to obtain the IP address automatically:

protected static void ChangeIPAndSubnet( IPAddress ipToSet, IPAddress subnetToSet )
{
    ManagementClass objMC = new ManagementClass("Win32_NetworkAdapterConfiguration");
    ManagementObjectCollection objMOC = objMC.GetInstances();

    // change the IP for all active ManagementObjects
    foreach (ManagementObject objMO in objMOC)
    {
        if ((bool)objMO["IPEnabled"])
        {
            try
            {
                ManagementBaseObject setIP;
                ManagementBaseObject newIP = objMO.GetMethodParameters("EnableStatic");

                // it's too bad that we have nice, neat ip addresses to use, only to change them
                // back to strings, but that's how this code works
                string ip_address = ipToSet.ToString();
                string subnet_mask = subnetToSet.ToString();

                newIP["IPAddress"] = new string[] { ip_address };
                newIP["SubnetMask"] = new string[] { subnet_mask };

                setIP = objMO.InvokeMethod("EnableStatic", newIP, null);
            }
            catch (Exception)
            {
                // report error
                string strError = "The IP Address and/or Subnet mask could not be changed.\n";
                strError += "Please check the values and try again";
                MessageBox.Show(strError, "Settings Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }
    }
}

How do I change the adapter settings to use an IP address (and subnet mask) I give it?