title: VB.NET must implement error
body: <p>I just convert the C# function to VB.NET function but somehow I get some error. Below is my C# function.</p>
  
  <pre><code>public abstract class BaseFilterControl: UserControl,IFilterControl
  {
      public string PropertyName { get; set; }
  
      public FilterDescriptorBase AssociatedDescriptor { get; set; }
  
      public bool IsFirst { get; set; }
  
      public abstract FilterDescriptorBase BuildDescriptor();
  
      protected abstract void Initialize();
  }
  </code></pre>
  
  <p>Below is my current VB function</p>
  
  <pre><code>Public MustInherit Class BaseFilterControl
      Inherits UserControl
      Implements IFilterControl
  
      Public Property PropertyName As String
  
      Public Property AssociatedDescriptor As FilterDescriptorBase
  
      Public Property IsFirst As Boolean
  
      Public MustOverride Function BuildDescriptor() As FilterDescriptorBase
  
      Protected MustOverride Sub Initialize()
  End Class
  </code></pre>
  
  <p>I got this error: </p>
  
  <pre><code>BaseFilterControl must implement Function BuildDescriptor() As FilterDescriptorBase.
  </code></pre>
  
  <p>Any idea. Please help. Thanks</p>