The type or namespace name 'ServiceController' could not be found

I am trying to check a service in C#, I have added the System.ServiceProcess.dll

Although I get the error:

Error 2 The type or namespace name 'ServiceController' could not be found (are you missing a using directive or an assembly reference?) D:\App\Form1.cs 247 13 App

My code is as follows:

private void button13_Click(object sender, EventArgs e)
{
    ServiceController sc = new ServiceController("Spooler");

    if (sc.Status == ServiceControllerStatus.Running)
    {
        MessageBox.Show("The service is running.");
    }
}

Do I perhaps need a "using" statement?