I got some code to refresh a image at certain time intervals, but it dosent seam to refresh the picture with the new one??

this is my code ... thanks

Code:
<HTML><BODY>

<!-- visionGS Script Code Begin --> 
<SCRIPT language="JavaScript" type="text/javascript">
var t = 5 // interval in seconds
image = "image.jpg" //name of the image 

function Start() {
tmp = new Date();
tmp = "?"+tmp.getTime()
document.images["visiongs"].src = image+tmp
setTimeout("Start()", t*1000)
}
</SCRIPT> 
<!-- visionGS Script Code End --> 

<IMG src=image.jpg border=1 name="visiongs">
</BODY>
</HTML>