title: T4. Error: An expression block evaluated as Null
body: <p>I've added template.tt file that looks like:</p>
  
  <pre><code>&lt;#@ template language="C#" debug="true" #&gt;
  &lt;#@ output extension=".cs" #&gt;
  &lt;#@ import namespace="System" #&gt;
  &lt;#@ import namespace="System.Collections.Generic" #&gt;
  
  using System;
  using System.Collections.Generic;
  
  namespace Test
  {
      public class &lt;#= this.ClassName#&gt;
      {       
  
      }
  }
  
  &lt;#+
      public string ClassName { get; set; }
  #&gt;
  </code></pre>
  
  <p>I'm receiving error:</p>
  
  <pre><code>An expression block evaluated as Null
  at Microsoft.VisualStudio.TextTemplating.ToStringHelper.ToStringWithCulture(Object objectToConvert)...
  </code></pre>
  
  <p>What should I do to avoid seeing these messages?</p>
  
  <p>Thanks in advance</p>