title: Getting a NullReferenceException Error when invoking a Select File Dialog Box
body: <p>This is a real newbie question. I have simple app that selects a picture and display's that picture in a PictureBox. </p>
  
  <p>I decided to mess with the Opacity Attribute so I added a timer and created this cool effect where the Main Form's Opacity is increased by 20% every 400 miliseconds. </p>
  
  <p>The problem is that now when I click the button that invokes the Select File Dialog Box I'm getting a NullReferenceException error. </p>
  
  <pre><code> private void tmrClock_Tick(object sender, EventArgs e)
      {
          if (ViewerForm.ActiveForm.Opacity != 1)
          {
          ActiveForm.Opacity = ActiveForm.Opacity + .20;
          }
      }
  </code></pre>
  
  <p>The error message is pointing to the if statement. </p>
  
  <p>What am I doing wrong? </p>
  
  <p>Thanks</p>