Assembly: How to dynamically load an Assembly that also depends on another assembly in C#

I want the main app to be able to load plugin1.dll which has dependency on

PlugingCore.dll but when I try using Assembly.LoadFile("c:\plugin1.dll"); I get an error:

('((System.Reflection.RuntimeAssembly)a).DefinedTypes' threw an exception of type 'System.Reflection.ReflectionTypeLoadException')

Note: both PluginCore.dll and Plugin1.dll are in same directory.