title: IsAssignableFrom() returns false when it should return true
body: <p>I am working on a plugin system that loads .dll's contained in a specified folder. I am then using reflection to load the assemblies, iterate through the types they contain and identify any that implement my <code>IPlugin</code> interface. </p>
  
  <p>I am checking this with code similar to the following: </p>
  
  <pre><code>foreach(Type t in myTypes )
  {
      if( typeof(IPlugin).IsAssignableFrom(t) )
      {
         ...
      }
  }
  </code></pre>
  
  <p>For some reason IsAssignableFrom() keeps returning false when it should be returning true. I have tried replacing the <code>t</code> by explicitly giving it a type that should pass, and it works fine, but for some reason it isn't working with the types that are returned from the loaded assembly. To make things stranger, the code works fine on my co-worker's machine but not on mine.</p>
  
  <p>Does anyone know of anything that might cause this sort of behavior?</p>
  
  <p>Thanks</p>