[SOLVED] Unknown property error within item renderer's data property

I'm using an item renderer, but keep getting this actionscript error:

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]

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...

This is how the itemrenderer looks:

<?xml version="1.0" encoding="utf-8"?>
<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">
<fx:Script>
   <![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 + "&skill=" + data.skillId ;

                 trace("http://localhost/sourcefoliocom.adobe.flexbuilder.project.flexbuilder/bindebug/php/getAllProjectsByUserSkill.php?id="+ data.userId + "&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");
}

  ]]>
</fx:Script>

<fx:Declarations>
    <s:HTTPService id="http_projects"
               method="GET" />
</fx:Declarations>

<s:states>
    <s:State name="login_preview_state"/>
<s:State name="login_opened_state"/>
<s:State name="login_edit_state"/>
</s:states>
<s:layout.login_opened_state>
    <s:VerticalLayout horizontalAlign="right"/>
</s:layout.login_opened_state>

<!-- login_opened_state -->
<s:SkinnableContainer includeIn="login_opened_state" width="100%" height="80">
    <s:layout>
    <s:HorizontalLayout gap="20" paddingBottom="20" paddingLeft="20" paddingRight="20" paddingTop="20" verticalAlign="middle"/>
</s:layout>
<s:Label fontSize="20" fontWeight="bold" text="{data.skillName}"/>
<s:Label fontSize="20" text="junior"/>
<s:Spacer width="100%" height="10"/>
<s:Image id="img_edit_open" width="20" height="20" source="images/edit.png" buttonMode="true" useHandCursor="true"/>
<s:Image id="img_foldin_open" width="20" height="20" buttonMode="true" source="images/foldin.png" useHandCursor="true"/>
</s:SkinnableContainer>
<s:VGroup id="vg_opened" 
      visible="false" 
      width="900" height="1000" gap="0"
      horizontalAlign="right">
 <mx:VBox>
     <mx:Repeater id="rpt_projects" width="100%">
         <components:Project currentItem= {rpt_projects.currentItem}" loggedin="true"/>
     </mx:Repeater>
     <components:AddProject />
    </mx:VBox>
<s:Image x="824" width="76" height="51" source="images/edit_flag.png" useHandCursor="true"/>
</s:VGroup>  
</s:ItemRenderer>

The error is thrown at this line:

<s:Label fontSize="20" fontWeight="bold" text="{data.skillName}"/>

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.

Do you need to see more code or some more info? Let me know!