No preview image

I'm using Jwplayer and love it. The only problem is that my preview image doesn't appear in the player- I just get the usual black screen and white arrow.

Below is the only stuff I embed in my webpage.

<!-- START OF THE PLAYER EMBEDDING TO COPY-PASTE --></p>
<div style="text-align: center;">
<embed src="player-viral.swf" type="application/x-shockwave-flash"
name="player2" allowscriptaccess="always" allowfullscreen="true"
flashvars="file=Explorer.flv&image=Sun RA.jpg"
align="bottom" height="315" width="400"><!-- END OF THE PLAYER EMBEDDING -->