title: What is happening with Polymorphism in C#
body: <p>I have an Interface [a] and a Implementer class [b]. [b] have its own methods apart of the implemented ones.</p>
  
  <pre><code>//-----------
  public interface a
  {
  void functionA();
  }
  //-----------
  
  public class b:a
  {
  void functionA(){}
  void functionB(){}
  
  }
  //------------
  </code></pre>
  
  <p>In project X inside the solution. When I code: [project is a class library]</p>
  
  <pre><code>a test = new b();
  test.functionB(); //It Works
  </code></pre>
  
  <p>In another project with a references to the library [Console application] </p>
  
  <pre><code>a test = new b();
  test.functionB(); //Error CS1061 --&gt; a doesn't have a method called function b
  </code></pre>
  
  <p>Sorry but names are  in spanish. Interface: pastebin.com/Unm5Adkd, Implementer: pastebin.com/wmikck9H, Program: Console app: pastebin.com/Yus91hQL... Thanks everyone for your help. :P</p>