title: Excel 2007 3-color scale with negative values
body: <p>Given the following data</p>
  
  <pre><code>values
   12
   2
   0
  -2
  -12
  </code></pre>
  
  <p>I want to add a 3-color scale conditional formatting to the values column such that cells</p>
  
  <pre><code>&lt; 0 are green
  = 0 are white
  &gt; 0 are red
  </code></pre>
  
  <p>Using formulas like</p>
  
  <pre><code>=$A$1&lt;0 for Minimum
  =$A$1=0 for Midpoint
  =$A$1&gt;0 for Masximum
  </code></pre>
  
  <p>does not seem to work.  cell value > 0 is red, cell &lt; 0 is green, but cell = 0 is NOT white (it is green)</p>
  
  <p>What's the right way to define the formulas?</p>