How to load DLL and call its methods using C#.NET

// Unbox it to correct object

Type type = null;

String AssemblyDir = @"D:\Project\DataAccess.dll";

//AssemblyDir = AssemblyDir.TrimStart("file:\\".ToArray());

 Assembly a = Assembly.LoadFrom(AssemblyDir);

       type = a.GetType("DataAccess.DerivedClass");

   if (type != null)

       {

          BaseClass objBaseClass = (BaseClass)Activator.CreateInstance(type, args);

          resultCode = objBaseClass.MethodName(Parameters);

        }

       else

          {

              throw new Exception("Can't find correct type name or dll!"); // FATAL ERROR. Can't find correct type name or dll.

            }

Where  BaseClass is like

public class BaseClass : ICloneable

{

// this method is override by DerivedClass

 public virtual string MethodName( parameters )

 {

   throw new NotImplementedException();

 }

}

Where  DerivedClass is like

public class DerivedClass : BaseClass

{

public override sealed string MethodName(parameters)

{

// do something with parameters

}

}