Load Assembly with dependent references

In my application I have an interface called IPlugin. This interface is used to identify dlls in a Plugin-folder and load them at application-startup.

The IPlugin interface looks like:

public interface IPlugin
{
  string Name { get; }

  void Initialize();
}

In my main-application I've used the following code to load all dll-files which are located in the Plugins-folder:

internal List<IPlugin> LoadPlugins()
{
    List<IPlugin> plugins = new List<IPlugin>();

    foreach (string file in Directory.GetFiles("Plugins", "*.dll", SearchOption.TopDirectoryOnly))
    {
        Assembly assembly = Assembly.LoadFile(Path.GetFullPath(file));
        Type targetType = assembly.GetTypes().FirstOrDefault(type => type.GetInterfaces().Contains(typeof(IPlugin)));
        if (targetType != null)
        {
            IPlugin plugin = Activator.CreateInstance(targetType) as IPlugin;
            if (plugin != null)
            {
                plugins.Add(plugin);
            }
        }
    }
    return plugins;
}

This just works fine for dlls which don't need another dll.

Now I've created a plugin which has two dlls.

• Users.Interface
• Users.Plugin

Users.Plugin has a references to Users.Interface. In the Users.Plugin there is an implementation of IPlugin. So the Users.Plugin-Dll will be identified to be loaded by my LoadPlugins-Method.

Now I get a ReflectionTypeLoadException with the Users.Plugin-File at the line:

Type targetType = assembly.GetTypes().FirstOrDefault(type => type.GetInterfaces().Contains(typeof(IPlugin)));

The LoaderException tells me, that the assembly Users.Interface or a reference could not be found.

I've tried to use Assembly.LoadFrom(...) but this doesn't work either.

I've also tried this approach with no success.

Any ideas how I can load assemblies with all dependencies and then create an instance?