OK here is the long winded version.
Your script URL:
Your HTML source:
The browser knows the web page comes from the index.php file in the “/” directory.
Because you neglect to specify that the securimage.php file is in a different directory, the browser assumes it is in the same directory as index.php, and thus tries to get the image from http://www.mattaproductions.com/securimage_show.php - which returns a Not Found error.
So fix the URL used in index.php - sorry if I thought you would know I meant the one used in the HTML source generated by your PHP script.