title: Can Excel Conditional Formatting use UDFs in the condition?
body: <p>I have a cell in Excel that I want to format differently based on a user defined formula (UDF) - my formula tests whether there is a formula in the cell...</p>
  
  <p>I am trying to use conditional formatting with my UDF to format the cell - but it does not seem to be working.</p>
  
  <p>My condition is this:</p>
  
  <pre><code>="isManualPrice(R22C12)"
  </code></pre>
  
  <p>I tried without the quotes, but get the error</p>
  
  <blockquote>
    <p>You cannot use references to other
    worksheets or workbooks for
    Conditional Formatting criteria</p>
  </blockquote>
  
  <p>Perhaps the issue relates to my UDF being defined in a separate macro workbook and not my main workbook...</p>
  
  <p>I see its mentioned in this <a href="http://blogs.msdn.com/excel/archive/2005/10/13/480599.aspx" rel="nofollow noreferrer">blog entry from 2005</a>, but only in passing...</p>
  
  <p>Thanks in advance.
  Chris</p>