Weirdness using sorter.sort for custom object list.

I have a velocity script as follows:

#set ($rawList = $CstPolicyList)
#set ($sortedList = $sorter.sort($rawList,"policySaleDate:desc")) 
Here is Sorted List: 
#if($sortedList.size() > 0)
  <table>
  <tr><th>ID</th><th>Sale Date</th></th></tr>
  #foreach($policy in $sortedList)
  <tr>
    <td> $policy.policyId</td> 
    <td>$!policy.policySaleDate </td>
    </tr>
  #end
  </table>
#else
  Sorted list is empty! <br>
#end
---------
Here is Raw List: 
#if($rawList.size() > 0)
  <table>
  <tr><th>ID</th><th>Sale Date</th></th></tr>
  #foreach($policy in $rawList)
  <tr>
    <td> $policy.policyId</td> 
    <td>$!policy.policySaleDate </td>
   </tr>
  #end
  </table>
#end

policySaleDate is a Marketo Date field.  It may be empty.

When I run it, I get output for the second, "rawList".  But nothing for the sorted list (size is 0).

Even weirder, if I change the sort column to use updatedAt:

 $sorter.sort($rawList,"updatedAt:desc")) 

Or to

 $sorter.sort($rawList,"updatedAt:asc")) 

$sorter.sort($rawList,"updatedAt:desc"))

Then I get Identical output for both the sortedList and the rawList.  The "asc" and "desc" do not make a difference.

Why would the sort not return anything if I reference the "policySaleDate" field?  I know it is the correct name (and I have the check box checked in the list)

because the data shows up in the email for the $rawList

Message was edited by: Digital Pi fixed some typos