Using imagecanvas on video screen but controls disappeared?

Sub main()

	port = CreateObject("roMessagePort")
    screen = CreateObject("roVideoScreen") 
   
   episode=CreateObject("roAssociativeArray")
   episode.HDBranded = false
   episode.IsHD = false 
  
 
episode.Stream = { url:"http://download.wavetlan.com/SVV/Media/HTTP/H264/Other_Media/H264_test5_voice_mp4_480x360.mp4",
bitrate:2000
quality:false
contentid:"mycontent-2000"
}
episode.StreamFormat= "mp4"
canvasItems = [
      
        { 
            Text:"The Server will go down"
            TextAttrs:{Color:"#0000000", Font:"Medium",
            HAlign:"HCenter", VAlign:"VCenter",
            Direction:"LeftToRight"}
            TargetRect:{x:390,y:357,w:500,h:60}
        }
    ] 
    canvasItems1 = [
      
        { 
            Text:"Hello ImageCanvas"
            TextAttrs:{Color:"#0000000", Font:"Medium",
            HAlign:"HCenter", VAlign:"VCenter",
            Direction:"LeftToRight"}
            TargetRect:{x:390,y:357,w:500,h:60}
        }
    ] 
 
   canvas = CreateObject("roImageCanvas")
   'port = CreateObject("roMessagePort")
   canvas.SetMessagePort(port)
   'Set opaque background
  ' canvas.SetLayer(0, {Color:"#FF000000", CompositionMode:"Source"}) 
   'canvas.SetRequireAllImagesToDraw(true)
   
    
    screen.SetContent(episode)
    screen.SetMessagePort(port)
    screen.Show() 
'   ' canvas.SetLayer(0, { Color: "#80000000", CompositionMode: "Source" })
    canvas.SetLayer(0, canvasItems)
    canvas.Show() 
   
   
    while true
       msg = wait(0, port)
         index = msg.GetIndex()
       if type(msg) = "roVideoScreenEvent" then
           print "showVideoScreen | Playback position = "; msg.isPlaybackPosition() " | index = "; msg.GetIndex()
           if msg.isScreenClosed()
               print "Screen closed"
               exit while
            else if msg.isStatusMessage()
                  print "status message: "; msg.GetMessage()
            else if msg.isPlaybackPosition()
                  print "playback position: "; msg.GetIndex()
            
					
            else if msg.isStreamSegmentInfo()
                  print "playback info"
                  print msg.GetMessage()
                  exit while
            else if msg.isPartialResult()
                  print "playback interrupted"
                  exit while
            else if msg.isRequestFailed()
                  print "request failed – error: "; msg.GetIndex();" – "; msg.GetMessage()
                  exit while
             
            end if
       end if
    end while 
    
    
   

End Sub