click item of the playlistitem, but it cant play the video which i select

Question

I use the expression web 4 to creat a silverlight video with its template,but when i run this in the web,i try to click the second vedio from the playlistitem,it cant play....

Pleas tell me how to do............

this is the code in the html:

<object data="data:application/x-silverlight-2," type="application/x-silverlight-2" width="320" height="240">
   <param name="source" value="silverlightvideos/ArchetypeTemplate.xap"/>
   <param name="background" value="white" />
   <param name="minRuntimeVersion" value="4.0.50401.0" />
   <param name="autoUpgrade" value="true" />
   <param name="enableHtmlAccess" value="true" />
   <param name="enableGPUAcceleration" value="true" />
   <param name="initparams" value='playerSettings =
  <Playlist>
   <DisplayTimeCode>false</DisplayTimeCode>
<EnableCachedComposition>true</EnableCachedComposition>
<EnableCaptions>true</EnableCaptions>
<EnableOffline>true</EnableOffline>
<EnablePopOut>true</EnablePopOut>
<StartMuted>false</StartMuted>
<StartWithPlaylistShowing>true</StartWithPlaylistShowing>
<StretchNonSquarePixels>NoStretch</StretchNonSquarePixels>
   <Items>
    <PlaylistItem>
     <AudioCodec>WmaProfessional</AudioCodec>
     <Description></Description>
     <FileSize>30278504</FileSize>
     <FrameRate>20</FrameRate>
     <Height>800</Height>
     <IsAdaptiveStreaming>false</IsAdaptiveStreaming>
     <MediaSource>http://172.17.148.129:1024/images/p0011ba8ba3.p201.1[1].mp4</MediaSource>
     <ThumbSource></ThumbSource>
     <Title></Title>
     <VideoCodec>VC1</VideoCodec>
     <Width>800</Width>
     </PlaylistItem>
     
     <PlaylistItem>
     <AudioCodec>WmaProfessional</AudioCodec>
     <Description></Description>
     <FileSize>30278504</FileSize>
     <FrameRate>20</FrameRate>
     <Height>800</Height>
     <IsAdaptiveStreaming>false</IsAdaptiveStreaming>
     <MediaSource>silverlightvideos/mrtexi.avi.wmv</MediaSource>
     <ThumbSource></ThumbSource>
     <Title></Title>
     <VideoCodec>VC1</VideoCodec>
     <Width>800</Width>
    </PlaylistItem>

    
   </Items>
  </Playlist>'/>
<a href="" style="text-decoration: none;">
   <img src="" alt="获取 Microsoft Silverlight" style="border-style: none;"/>
  </a>
   </object>