title: how ... if statement and button content "WP7"
body: <p>What is the right way to do this? This way is not working:</p>
  
  <pre><code>if (((String)enterAmountButton.Content) == "")
   MessageBox.Show("Please enter the total bill amount.");
  else if (((String)enterTipButton.Content) == "")
   MessageBox.Show("Please enter the tip % amount.");   
  </code></pre>
  
  <p>this way is not working neither:</p>
  
  <pre><code>if (enterAmountButton.Content == "")   
   MessageBox.Show("Please enter the total bill amount.");   
  else if (enterTipButton.Content == "")   
   MessageBox.Show("Please enter the tip % amount.");   
  </code></pre>