AppDomain Loading Error

I got loading problem and can't resolve it. The Error I got is as follows:Could not load file or assembly 'BuildTest, Version=1.0.0.4, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified.":"BuildTest, Version=1.0.0.4, Culture=neutral, PublicKeyToken=null"

The code I wrote is as follows:

        var buildTestPath = @"D:\BuildTest\bin\Debug";

        AppDomainSetup setup = new AppDomainSetup();
        setup.ApplicationName = "BuildTest";
        setup.ShadowCopyFiles = "true";
        setup.PrivateBinPath = buildTestPath;

        AppDomain domain = AppDomain.CreateDomain("MyDomain", AppDomain.CurrentDomain.Evidence, setup);

        var assemblyFile = Path.Combine(buildTestPath, "BuildTest.dll");
        var assemblyName = AssemblyName.GetAssemblyName(assemblyFile);
        var assembly = domain.Load(assemblyName);

        Type myType = assembly.GetType("BuildTest.Class1");
        MethodInfo myMethod = myType.GetMethod("MethodA");
        object obj = Activator.CreateInstance(myType);
        myMethod.Invoke(obj, null);

        AppDomain.Unload(domain);

Could anyone help me out?

Thanks