[flexcoders] Cannot access a property or method of a null object reference

[Roger Ross]

Hello,

Working my way throught the "Training From the Source" turorial and
ran into this error message.

Not sure why I am getting it. I compared my code to the completed code
for the lesson and it looks the same with no problems when I compile it.


TypeError: Error #1009: Cannot access a property or method of a null
object reference.
        at Dashboard/::catHandler()
        at Dashboard/__catRPC_result()
        at
flash.events::EventDispatcher/flash.events:EventDispatcher::dispatchEventFunction()
        at flash.events::EventDispatcher/dispatchEvent()
        at
mx.rpc.http.mxml::HTTPService/http://www.adobe.com/2006/flex/mx/internal::dispatchRpcEvent()
        at
mx.rpc::AbstractInvoker/http://www.adobe.com/2006/flex/mx/internal::resultHandler()
        at mx.rpc::Responder/result()
        at mx.rpc::AsyncRequest/acknowledge()
        at ::DirectHTTPMessageResponder/completeHandler()
        at
flash.events::EventDispatcher/flash.events:EventDispatcher::dispatchEventFunction()
        at flash.events::EventDispatcher/dispatchEvent()
        at flash.net::URLLoader/flash.net:URLLoader::onComplete()


Here is a copy of the code that it has me write with the comboBox that
is to receive the data:
 

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml";
layout="horizontal"
        creationComplete="catRPC.send()">

<mx:Script>
        <![CDATA[
                import mx.collections.ArrayCollection;
                import mx.rpc.events.ResultEvent;
                
                [Bindable]
                private var categories:ArrayCollection=new ArrayCollection();
        
                private function catHandler(event:ResultEvent):void{
                categories = event.result.catelog.category;
                var catObj:Object = new Object();
                catObj.name = "All";
                catObj.categoryID = 0;
                categories.addItemAt(catObj, 0);
                catCombo.selectedIndex = 0;
                }
                
        ]]>
</mx:Script>

        <mx:HTTPService id="catRPC"
        url="http://www.flexgrocer.com/category.xml";
        result="catHandler(event)"/>


<mx:ComboBox id="catCombo"
   dataProvider="{categories}"
   labelField="name"/>


Any Idea's…

Thanks,

Roger