title: Unknown property error within item renderer's data property
body: <p>I'm using an item renderer, but keep getting this actionscript error:</p>
  
  <pre><code>Error: Unknown Property: 'skillName'. at mx.collections::ListCollectionView/http://www.adobe.com/2006/actionscript/flash/proxy::getProperty()[E:\dev\4.y\frameworks\projects\framework\src\mx\collections\ListCollectionView.as:870]
         at mx.binding::PropertyWatcher/updateProperty()[E:\dev\4.y\frameworks\projects\framework\src\mx\binding\PropertyWatcher.as:338]
         at Function/http://adobe.com/AS3/2006/builtin::apply()
         at mx.binding::Watcher/wrapUpdate()[E:\dev\4.y\frameworks\projects\framework\src\mx\binding\Watcher.as:192]
         at mx.binding::PropertyWatcher/updateParent()[E:\dev\4.y\frameworks\projects\framework\src\mx\binding\PropertyWatcher.as:239]
         at mx.binding::Watcher/updateChildren()[E:\dev\4.y\frameworks\projects\framework\src\mx\binding\Watcher.as:138]
         at mx.binding::PropertyWatcher/updateProperty()[E:\dev\4.y\frameworks\projects\framework\src\mx\binding\PropertyWatcher.as:347]
         at Function/http://adobe.com/AS3/2006/builtin::apply()
         at mx.binding::Watcher/wrapUpdate()[E:\dev\4.y\frameworks\projects\framework\src\mx\binding\Watcher.as:192]
         at mx.binding::PropertyWatcher/eventHandler()[E:\dev\4.y\frameworks\projects\framework\src\mx\binding\PropertyWatcher.as:375]
         at flash.events::EventDispatcher/dispatchEventFunction()
         at flash.events::EventDispatcher/dispatchEvent()
         at mx.core::UIComponent/dispatchEvent()[E:\dev\4.y\frameworks\projects\framework\src\mx\core\UIComponent.as:13152]
         at spark.components::DataRenderer/set data()[E:\dev\4.y\frameworks\projects\spark\src\spark\components\DataRenderer.as:123]
         at spark.components::SkinnableDataContainer/updateRenderer()[E:\dev\4.y\frameworks\projects\spark\src\spark\components\SkinnableDataContainer.as:606]
         at spark.components.supportClasses::ListBase/updateRenderer()[E:\dev\4.y\frameworks\projects\spark\src\spark\components\supportClasses\ListBase.as:1106]
         at spark.components::DataGroup/setUpItemRenderer()[E:\dev\4.y\frameworks\projects\spark\src\spark\components\DataGroup.as:1157]
         at spark.components::DataGroup/initializeTypicalItem()[E:\dev\4.y\frameworks\projects\spark\src\spark\components\DataGroup.as:327]
         at spark.components::DataGroup/ensureTypicalLayoutElement()[E:\dev\4.y\frameworks\projects\spark\src\spark\components\DataGroup.as:384]
         at spark.components::DataGroup/measure()[E:\dev\4.y\frameworks\projects\spark\src\spark\components\DataGroup.as:1467]
         at mx.core::UIComponent/http://www.adobe.com/2006/flex/mx/internal::measureSizes()[E:\dev\4.y\frameworks\projects\framework\src\mx\core\UIComponent.as:8506]
         at mx.core::UIComponent/validateSize()[E:\dev\4.y\frameworks\projects\framework\src\mx\core\UIComponent.as:8430]
         at mx.managers::LayoutManager/validateSize()[E:\dev\4.y\frameworks\projects\framework\src\mx\managers\LayoutManager.as:665]
         at mx.managers::LayoutManager/doPhasedInstantiation()[E:\dev\4.y\frameworks\projects\framework\src\mx\managers\LayoutManager.as:816]
         at mx.managers::LayoutManager/doPhasedInstantiationCallback()[E:\dev\4.y\frameworks\projects\framework\src\mx\managers\LayoutManager.as:1180]
  </code></pre>
  
  <p>The weird thing is that it worked fine, until at a certain point I kept getting this error, out of the blue. I've been searching for it on Google and Stackoverflow and struck upon a few websites, but none of the answers could help me get any further. It seems this error is also mostly thrown in mobile AIR projects, but mine is a Flash Player project...  </p>
  
  <p>This is how the itemrenderer looks:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;s:ItemRenderer xmlns:fx="http://ns.adobe.com/mxml/2009"
              xmlns:s="library://ns.adobe.com/flex/spark"
              xmlns:mx="library://ns.adobe.com/flex/mx"
              xmlns:components="components.*"
              width="100%" height="100%" autoDrawBackground="true"
              creationComplete="creationCompleteHandler(event)"
              height.login_edit_state="80"
                              color.login_edit_state="#000000"
              height.login_preview_state="80"&gt;
  &lt;fx:Script&gt;
     &lt;![CDATA[
        import mx.collections.ArrayCollection;
    import mx.controls.Alert;
    import mx.events.FlexEvent;
    import mx.rpc.events.FaultEvent;
    import mx.rpc.events.ResultEvent;
    import mx.utils.ArrayUtil;
  
    public var loggedin:Boolean = true;
  
    [Bindable]private var ac_projects:ArrayCollection;
  
    protected function creationCompleteHandler(event:FlexEvent):void
    {
       currentState = "login_preview_state";
       img_foldout_preview.addEventListener(MouseEvent.CLICK, changeState);
       img_edit_preview.addEventListener(MouseEvent.CLICK, changeState);
  
       http_projects.addEventListener(ResultEvent.RESULT, http_projects_resultEvent);
       http_projects.addEventListener(FaultEvent.FAULT, http_projects_faultEvent);
       http_projects.url = "http://localhost/sourcefoliocom.adobe.flexbuilder.project.flexbuilder/bindebug/php/getAllProjectsByUserSkill.php?id=" + data.userId + "&amp;skill=" + data.skillId ;
  
                   trace("http://localhost/sourcefoliocom.adobe.flexbuilder.project.flexbuilder/bindebug/php/getAllProjectsByUserSkill.php?id="+ data.userId + "&amp;skill=" + data.skillId);
       http_projects.send();
  }
  
  protected function http_projects_resultEvent(event:ResultEvent):void
  {
     ac_projects = new ArrayCollection(ArrayUtil.toArray(event.result.projects.project));
         rpt_projects.dataProvider = ac_projects; 
  }
  
  protected function http_projects_faultEvent(event:FaultEvent):void
  {
      trace("Kon projecten niet laden");
  }
  
    ]]&gt;
  &lt;/fx:Script&gt;
  
  &lt;fx:Declarations&gt;
      &lt;s:HTTPService id="http_projects"
                 method="GET" /&gt;
  &lt;/fx:Declarations&gt;
  
  &lt;s:states&gt;
      &lt;s:State name="login_preview_state"/&gt;
  &lt;s:State name="login_opened_state"/&gt;
  &lt;s:State name="login_edit_state"/&gt;
  &lt;/s:states&gt;
  &lt;s:layout.login_opened_state&gt;
      &lt;s:VerticalLayout horizontalAlign="right"/&gt;
  &lt;/s:layout.login_opened_state&gt;
  
  &lt;!-- login_opened_state --&gt;
  &lt;s:SkinnableContainer includeIn="login_opened_state" width="100%" height="80"&gt;
      &lt;s:layout&gt;
      &lt;s:HorizontalLayout gap="20" paddingBottom="20" paddingLeft="20" paddingRight="20" paddingTop="20" verticalAlign="middle"/&gt;
  &lt;/s:layout&gt;
  &lt;s:Label fontSize="20" fontWeight="bold" text="{data.skillName}"/&gt;
  &lt;s:Label fontSize="20" text="junior"/&gt;
  &lt;s:Spacer width="100%" height="10"/&gt;
  &lt;s:Image id="img_edit_open" width="20" height="20" source="images/edit.png" buttonMode="true" useHandCursor="true"/&gt;
  &lt;s:Image id="img_foldin_open" width="20" height="20" buttonMode="true" source="images/foldin.png" useHandCursor="true"/&gt;
  &lt;/s:SkinnableContainer&gt;
  &lt;s:VGroup id="vg_opened" 
        visible="false" 
        width="900" height="1000" gap="0"
        horizontalAlign="right"&gt;
   &lt;mx:VBox&gt;
       &lt;mx:Repeater id="rpt_projects" width="100%"&gt;
           &lt;components:Project currentItem= {rpt_projects.currentItem}" loggedin="true"/&gt;
       &lt;/mx:Repeater&gt;
       &lt;components:AddProject /&gt;
      &lt;/mx:VBox&gt;
  &lt;s:Image x="824" width="76" height="51" source="images/edit_flag.png" useHandCursor="true"/&gt;
  &lt;/s:VGroup&gt;  
  &lt;/s:ItemRenderer&gt;
  </code></pre>
  
  <p>The error is thrown at this line:</p>
  
  <pre><code>&lt;s:Label fontSize="20" fontWeight="bold" text="{data.skillName}"/&gt;
  </code></pre>
  
  <p>The ArrayCollection filling up this renderer is an xml file my own webservice returns. I've tested the file and the use of skillName should be correct in this case.</p>
  
  <p>Do you need to see more code or some more info? Let me know!</p>