Error in compliation - Flex2 builder (getting started lessons)

Question

I am following the lessons given in the Flex2 builder
tutorial. I get an error during compilation. The error reads
"Multiple markers at this line;
- Line breakpoint: BlogReader.mxml[line: 15]
- 1120: Access of undefined property dgPosts."
Can somebody pse help. My codes are below. The error lines
are line15 and line 16. I m a newbee at this. Thanks.
1. <?xml version="1.0" encoding="utf-8"?>
2. <mx:Application xmlns:mx="
http://www.adobe.com/2006/mxml"
layout="absolute" creationComplete="feedRequest.send()">
3. <mx:HTTPService
4. id="feedRequest"
5. url="
http://weblogs.macromedia.com/mchotin/index.xml"
6. useProxy="false"/>
7.
8. <mx:Panel x="10" y="10" width="475" height="400"
layout="absolute"
title="{feedRequest.lastResult.rss.channel.title}">
9. <mx:DataGrid x="20" y="20" width="400"
dataProvider="{feedRequest.lastResult.rss.channel.item}" >
10. <mx:columns>
11. <mx:DataGridColumn headerText="Posts"
dataField="title" />
12. <mx:DataGridColumn headerText="Date"
dataField="pubDate" width="150" />
13. </mx:columns>
14. </mx:DataGrid>
15. <mx:TextArea x="20" y="175" width="400"
htmlText="{dgPosts.selectedItem.description}" />
16. <mx:LinkButton x="20" y="225" label="Read Full Post"
click="navigateToURL(new URLRequest(dgPosts.selectedItem.link));"
/>
17. </mx:Panel>
18. </mx:Application>

Answer 1

Thanks very much, Tarnch and Awclemen. I missed that
in the tutorial.