// CS1540.cs
public class Base
{
   protected void MethodA()
   {
   }
}

public class Derived : Base
{
   public static void test(Base anotherInstance)
   // FIX #1: Change the method declaration as follows
   // public static void test(Derived anotherInstance)
   {
      anotherInstance.MethodA();   // CS1540
   }
}

public class Tester : Derived
{
   public static void Main()
   {
      Base myBaseClass = new Base();
      // FIX #2: Change the new object creation as follows
      // Derived myBaseClass = new Derived();
      test(myBaseClass);
   }
}