PopUpEvent class confusion

I am using the Cairngorm Popup 1.0 library and have defined a popup like:

  <popup:PopUpWrapper id="newObjectClass" center="true" modal="true"

                                     closed="newObjectClassClosedHandler(event)">
    <uid:NewObjectDialog id="newObjectDialog"/>
  </popup:PopUpWrapper>

However when I try to compile this I get an error like:

[ERROR] /home/k/dev/src/flex-application/src/main/flex/Editor.mxml:[142,-1] Event type 'com.adobe.popup:PopUpEvent' is unavailable.

If I removing the 'closed' attribute on the PopUpWrapper compilation succeeds.

When I look at the library's PopUpBase I see that the following is declared:

[Event(name="closed",type="com.adobe.popup.PopUpEvent")]

I cannot find the class com.adobe.popup.PopUpEvent although I do see that the library includes class com.adobe.cairngorm.popup.PopUpEvent.  Is the Event declaration in PopUpBase incorrect or am I missing something?

Thanks