title: no suitable method found to override error with partial class
body: <p>i need to define a class partially in seperate assemblies. actually i need to redefine a class partially, that is already defined in an assembly written in C++ Cli, but this is maybe a different question.<br>
  for the case, all codes written in c#, i have a baseclass definition in basenamespace assembly</p>
  
  <pre><code>using System;
  
  namespace BaseNameSpace
  {
    public class BaseClass
    {
      public int Num;
      public double dNum;
      public BaseClass(int s, double d)
      {
        Num = s;
        dNum = d;
      }
  
      public virtual void Wrt()
      {
        Console.WriteLine("{0},{1}", Num, dNum);
      }
    }
  }
  </code></pre>
  
  <p>i add another assembly project called derivedclassSpace and declare a derivedclass derived from baseclass. i also add a partial class definition to this project.</p>
  
  <pre><code>using System;
  using BaseNameSpace;
  
  namespace BaseNameSpace
  {
    public partial class BaseClass
    {
      public void Mult()
      {
        Num *= 2;
      }
    }
  }
  
  namespace DerivedNameSpace
  {
    public class DerivedClass : BaseClass
    {
      public DerivedClass(int s)
        : base(s, 0)
      {
  
      }
  
      public override void Wrt()
      {
  
        Mult(); // mult line
        base.Wrt();
      }
    }
  }
  </code></pre>
  
  <p>when i build the solution i get </p>
  
  <blockquote>
    <p>'DerivedNameSpace.DerivedClass.Wrt()':
    no suitable method found to override</p>
  </blockquote>
  
  <p>if i remove the partial class lines and mult line, everything is normal.<br>
  am i using the concept of partial keyword? how can i get rid of the error?</p>