Having Trouble With A Simple ScreenSaver

Hi. I seem to be having trouble with what looks like an incredibly simple screensaver. Here is the code:

' Main() is useful for testing screensaver. It should be commented
' out before this is checked in.

'Sub Main()
'	ShowScreenSaver()
'End Sub

' The screensaver entry point.
Sub RunScreenSaver()
	ShowScreenSaver()
End Sub

Sub ShowScreenSaver() 
	' Works With Images
	facade = CreateObject("roParagraphScreen")
	facade.Show()
	m.canvas = CreateObject("roImageCanvas")
	canvas_size = m.canvas.GetCanvasRect()
	m.canvas.Show()
	while(true)
		date = CreateObject("roDateTime")
		m.canvas.SetLayer(1,{	url: "http://somesite.com/WeeklyFinal.png?&nocache=" + date.AsSeconds().ToStr()
					CompositionMode: "Source"
					TargetRect: {x:0,y:0,w:canvas_size.w,h:canvas_size.h}})
		' Sleep For 30 Seconds
		sleep(30000)
	end while
	m.canvas.Close()
End Sub
 

When I run the ShowScreenSaver from the Main subroutine it shows the WeeklyFinal.png image and updates it every 30 seconds. However, when I comment out the Main routine and run ShowScreenSaver from the RunScreenSaver subroutine all I get is a blank screen when I preview the screensaver.

Does anyone have any ideas. I'm sure I'm just being an imbecile.