erase images from screen  in vb.net

I am using silverlight vb.net

I tried this delay but what happens is that screen wont erase and the delay will start. Like the
i can erase images from the screen using   canvas1.Children.Remove(img1). and what i cant do is pause  for 5 seconds  so I dont write new images to screen for 5 secons after i erase the old ones.

'eraseScreen() wont start until after the below delay has finshed?



eraseScreen() 'wont work until after the delay has happened why?

  sttime = Now
  edtime = Now.AddSeconds(5)

  While edtime > sttime
              tb.Text = "Level " & levelCount
               sttime = Now
   End WhileStart Free Trial