thumb.php does not pull the picture

Hey,
I have been trying to show the pictues I upload also as a thumbnail. The following php file is supposed to pull the picture and resizes it:

<?php

// TimThumb script created by Tim McDaniels and Darren Hoyt with tweaks by Ben Gillbanks
// https://code.google.com/p/timthumb/

// MIT License: https://www.opensource.org/licenses/mit-license.php

/* Parameters allowed: */

// w: width
// h: height
// zc: zoom crop (0 or 1)
// q: quality (default is 75 and max is 100)

// HTML example: <img src="/scripts/timthumb.php?src=/images/whatever.jpg&w=150&h=200&zc=1" alt="" />

if( !isset( $_REQUEST[ "src" ] ) ) { die( "no image specified" ); }

// clean params before use
$src = $_REQUEST['src'];
// possibles?
//$src = preg_replace( "/^(\.+(\/|))+/", "", $src );
//$src = str_replace( "../", "", $src );
//$src = preg_replace( '/^(s?f|ht)tps?:\/\/[^\/]+/i', '', $src );
$src = preg_replace( "/(?:^\/+|\.{2,}\/+?)/", "", $src );
$src = preg_replace( '/^\w+:\/\/[^\/]+/', '', $src );
$new_width = preg_replace( "/[^0-9]+/", "", $_REQUEST[ 'w' ] );
$new_height = preg_replace( "/[^0-9]+/", "", $_REQUEST[ 'h' ] );
$zoom_crop = preg_replace( "/[^0-9]+/", "", $_REQUEST[ 'zc' ] );

if( !isset( $_REQUEST['q'] ) ) { $quality = 80; } else { $quality = preg_replace("/[^0-9]/", "", $_REQUEST['q'] ); }

// set path to cache directory (default is ./cache)
// this can be changed to a different location
$cache_dir = './cache';

// get mime type of src
$mime_type = mime_type( $src );

// check to see if this image is in the cache already
check_cache( $cache_dir, $mime_type );

// make sure that the src is gif/jpg/png
if( !valid_src_mime_type( $mime_type ) ) {
	$error = "Invalid src mime type: $mime_type";
	die( $error );
}

// check to see if GD function exist
if(!function_exists('imagecreatetruecolor')) {
	$error = "GD Library Error: imagecreatetruecolor does not exist";
	die( $error );
}

// set document root
$doc_root = $_SERVER['DOCUMENT_ROOT'];

// get path to image on file system
$src = $doc_root . '/' . $src;

if(strlen($src) && file_exists( $src ) ) {

	// open the existing image
	$image = open_image($mime_type, $src);
	if ($image === false) { die ('Unable to open image : ' . $src ); }		

	// Get original width and height
	$width = imagesx($image);
	$height = imagesy($image);

	// generate new w/h if not provided
	if($new_width && !$new_height) {
		$new_height = $height * ($new_width/$width);
	}
	elseif($new_height && !$new_width) {
		$new_width = $width * ($new_height/$height);
	}
	elseif(!$new_width && !$new_height) {
		$new_width = $width;
		$new_height = $height;
	}

	// create a new true color image
	$canvas = imagecreatetruecolor($new_width, $new_height);

	if( $zoom_crop ) {

		$src_x = $src_y = 0;
		$src_w = $width;
		$src_h = $height;

		$cmp_x = $width  / $new_width;
		$cmp_y = $height / $new_height;

		// calculate x or y coordinate and width or height of source

		if ( $cmp_x > $cmp_y ) {

			$src_w = round( ( $width / $cmp_x * $cmp_y ) );
			$src_x = round( ( $width - ( $width / $cmp_x * $cmp_y ) ) / 2 );

		}
		elseif ( $cmp_y > $cmp_x ) {

			$src_h = round( ( $height / $cmp_y * $cmp_x ) );
			$src_y = round( ( $height - ( $height / $cmp_y * $cmp_x ) ) / 2 );

		}

		imagecopyresampled( $canvas, $image, 0, 0, $src_x, $src_y, $new_width, $new_height, $src_w, $src_h );

	}
	else {

		// copy and resize part of an image with resampling
		imagecopyresampled( $canvas, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height );

	}

	// output image to browser based on mime type
	show_image( $mime_type, $canvas, $quality, $cache_dir );

	// remove image from memory
	ImageDestroy( $canvas );

} else {

	if( strlen( $src ) ) { echo $src . ' not found.'; } else { echo 'no source specified.'; }

}

function show_image ($mime_type, $image_resized, $quality, $cache_dir) {

	// check to see if we can write to the cache directory
	$is_writable = 0;
	$cache_file_name = $cache_dir . '/' . get_cache_file();        	

	if( touch( $cache_file_name ) ) {
		// give 666 permissions so that the developer
		// can overwrite web server user
		chmod( $cache_file_name, 0666 );
		$is_writable = 1;
	}
	else {
		$cache_file_name = NULL;
		header('Content-type: ' . $mime_type);
	}

	if(stristr( $mime_type, 'gif' ) ) {
		imagegif( $image_resized, $cache_file_name );
	}
	elseif( stristr( $mime_type, 'jpeg' ) ) {
		imagejpeg( $image_resized, $cache_file_name, $quality );
	}
	elseif( stristr( $mime_type, 'png' ) ) {
		imagepng( $image_resized, $cache_file_name, ceil( $quality / 10 ) );
	}
	if( $is_writable ) { show_cache_file( $cache_dir, $mime_type ); }
	exit;

}

function open_image ($mime_type, $src) {

	if(stristr($mime_type, 'gif')) {
		$image = imagecreatefromgif($src);
	}
	elseif(stristr($mime_type, 'jpeg')) {
		$image = imagecreatefromjpeg($src);
	}
	elseif(stristr($mime_type, 'png')) {
		$image = imagecreatefrompng($src);
	}
	return $image;

}

function mime_type( $file ) {

	$frags = split( "\.", $file );
	$ext = strtolower( $frags[ count( $frags ) - 1 ] );
	$types = array(
 		'jpg'  => 'image/jpeg',
 		'jpeg' => 'image/jpeg',
 		'png'  => 'image/png',
 		'gif'  => 'image/gif',
 		'bmp'  => 'image/bmp',
 		'doc'  => 'application/msword',
 		'xls'  => 'application/msword',
 		'xml'  => 'text/xml',
 		'html' => 'text/html'
 	);
	$mime_type = $types[ $ext ];
	if( !strlen( $mime_type ) ) { $mime_type = 'unknown'; }
	return $mime_type;

}

function valid_src_mime_type ( $mime_type ) {

	if( preg_match( "/jpg|jpeg|gif|png/i", $mime_type ) ) { return 1; }
	return 0;

}

function check_cache ( $cache_dir, $mime_type ) {

	// make sure cache dir exists
	if( !file_exists( $cache_dir ) ) {
		// give 777 permissions so that developer can overwrite
		// files created by web server user
		mkdir( $cache_dir );
		chmod( $cache_dir, 0777 );
	}

	show_cache_file( $cache_dir, $mime_type );

}

function show_cache_file ( $cache_dir, $mime_type ) {

    $cache_file = get_cache_file();

    if( file_exists( $cache_dir . '/' . $cache_file ) ) {

    	// check for updates
		$if_modified_since = preg_replace( '/;.*$/', '', $_SERVER[ "HTTP_IF_MODIFIED_SINCE" ] );
		$gmdate_mod = gmdate( 'D, d M Y H:i:s', filemtime( $cache_dir . '/' . $cache_file ) );
		if( strstr( $gmdate_mod, 'GMT' ) ) {
			$gmdate_mod .= " GMT";
		}

		//error_log("TimThumb: $gmdate_mod == $if_modified_since");

		if ( $if_modified_since == $gmdate_mod ) {
			header( "HTTP/1.1 304 Not Modified" );
			exit;
		}

    	// send headers then display image
    	header( "Content-Type: " . $mime_type );
    	header( "Last-Modified: " . gmdate( 'D, d M Y H:i:s', filemtime( $cache_dir . '/' . $cache_file ) . " GMT" ) );
    	header( "Content-Length: " . filesize( $cache_dir . '/' . $cache_file ) );
    	header( "Cache-Control: max-age=9999, must-revalidate" );
    	header( "Expires: " . gmdate( "D, d M Y H:i:s", time() + 9999 ) . "GMT" );
    	readfile( $cache_dir . '/' . $cache_file );
		exit;

    }

}

function get_cache_file () {

	$request_params = $_REQUEST;
	$cachename = $_REQUEST['src'] . $_REQUEST['w'] . $_REQUEST['h'] . $_REQUEST['zc'] . $_REQUEST['q'];
	$cache_file = md5( $cachename );
	return $cache_file;

}

?>

In the writing panel I have a custom field that says ‘Enter the URL of the picture that you want to auto-resize’. When I enter the URL it automatically creates a custom field with the name ‘image’. So basically everything should work.

But the thumbnail does not show up. Instead it shows a question mark on the homepage next to the article. I have been trying it since hours but I can’t figure out what’s wrong!! Any ideas?

do77