title: why ConfigurationManager not work on child project
body: <p>In a solution  I have three projects,you can see on picture.Want to access project-1 and project-2 from main project,use bellow syntax to show the desired project,but problem is when I try to find config file value show me error “Object reference not set to an instance of an object.”
  Note:individually each project work perfectly ,each project can fetch config file info with out showing any error.but they not work when goes from main project.</p>
  
  <p>Need help get config file value on each project</p>
  
  <p><strong>syntax use in main project</strong> </p>
  
  <pre><code>using UI2;
  using UI1;
  
        if (radioButton1.Checked)
                  {
                      UI1.Form1 fm = new UI1.Form1();
                      fm.Show();
  
                  }
                  if (radioButton2.Checked)
                  {
                      UI2.Form1 fm = new UI2.Form1();
                      fm.Show();
  
                  } 
  </code></pre>
  
  <p>If have any query please ask,thanks in advanced.</p>
  
  <p><img src="https://i.stack.imgur.com/EqeE8.png" alt="enter image description here"></p>