Generating graphics

I need to learn to create graphics on the fly in php4.2.2 so I decided to start by trying to draw a simple line.

I have not had much success.

I have listed the code below. If I include the header, I get an error message that says:

"Cannot add header information - headers already sent by (there is a line reference here for the line that says <?php)"

However, if I don't include the header I get a white page with nothing on it and no errors are generated.

I am a newbie and have no experience with graphics. Can someone please give me a few pointers? I have referred to php.net but I am confused by the advice as it covers so many different versions of php. My end goal is to draw graphs with data on dynamic pages using data from a mySQL Table.

Any advice would be greatly appreciated!

Here is the code:

<?php
Header ("Content-type: image/jpeg");
$image = @imagecreate(200,150) or die ("Cannot Initialize new image stream!");

$gray = ImageColorAllocate($image,204,204,204);
$blue = ImageColorAllocate($image,0,0,255);

ImageLine($image,10,10,15,30,$blue);

ImageJPEG($image);
ImageDestroy($image);
?>

Thank you!

Look ok..just make sure there is no whitespace before the first <? ...no spaces, new lines or anything....

There is no whitespace, etc. But still no results.

Can you think of anything else that might be causing the problem?
thanks

When I run this code here, it runs perfectly. What version of PHP are you using? Can you provide a link to the page that is not working?

do you have the GD library installed?