title: Add picture in header to a .docx using novacode DocX
body: <pre><code>Header header_default = doc.Headers.first;
  Paragraph p1 = header_default.InsertParagraph();
  </code></pre>
  
  <p>I've tried to add a picture in my header in a word file. I tried it with: </p>
  
  <pre><code>p1.AppendPicture(picture);
  </code></pre>
  
  <p>And also with a table:</p>
  
  <pre><code>Table t1 = header_default.InsertTable(10,2);
  t1.Pictures.Add(picture);
  </code></pre>
  
  <p>Well the big problem is that the code never run to this place it's always crashing by inserting a paragraph to the header:</p>
  
  <pre><code>Paragraph p1 = header_default.InsertParagraph();
  </code></pre>
  
  <p>or</p>
  
  <pre><code>Table t1 = header_default.InsertTable(10,2);
  </code></pre>
  
  <p>Error: <code>System.NullReferenceException</code></p>
  
  <p>I'm new in .net and docx library hope someone can help me with the prblem</p>