Issue with buttons of Alerts

When I compile my project with KapInspect 1.5, the buttons of my Alerts show a label "null".
Just try this :
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml">

     <mx:Script>
     <![CDATA[

          import mx.controls.Alert;

          private function showAlert() :void             

     ]]>
     </mx:Script>

     <mx:Button label="Show alert" click="showAlert();" />

</mx:Application>

and add kapinspect.swc in the compilation.

I use FlashDevelop as IDE.

Here is a screenshot.

When I remove KapInspect.swc from the compilation libraries, buttons are ok.