Dynamically Generated Images ( PHPGraph ) and timeouts.

I'm using JPGraph in a PHP script, and I have caching turned on in JPGraph. The graph making PHP is called from a img tag like so: <img src="testgraph.php"> If JPGraph has determined that the image is too old, it regenerates it on the fly. Problem is, if the image takes more than 1-2 seconds for JPGraph to create, I get a broken image link in IE, and a blank image area in Mozilla. They're not waiting long enough for the image generation to finish and JPGraph to send the image. ( The images are small, and so download quickly, so it's not a DL issue ). Is there some way to tell the browser to wait for the image? A <meta> tag, or something? -Daniel