Problemi con upload di file

[safin75]

Ciao a tutti,
ho questo problema: dopo aver studiato, ho aggiornato e corretto questo script che effettua l'upload di fotografie, inserendo i dati nel mio db.
Lo provo in localhost e funziona perfettamente anche con le foto di grandi dimensioni, sono riuscito anche ad inserire le istruzioni che effettuano il resize e riducono la qualità per avere file più piccoli, ma ieri l'amara sorpresa:
caricato nel mio sito, lo script carica solo i file di piccola dimensione, provando quelli "più pesanti", tipo 3 MB o più lo script non carica nulla.
Mi aiutate a capire dove sbaglio? Grazie
Riporto interamente il file UPLOAD richiamato dal form

<?php

    define("IMAGE_QUALITY", 90);


    include("config.inc.php");

    // inizializzazione
    $result_final = "";
    $counter = 0;

    // List of our known photo types
    $known_photo_types = array( 
                        'image/pjpeg' => 'jpg',
                        'image/jpeg' => 'jpg',
                        'image/gif' => 'gif',
                        'image/bmp' => 'bmp',
                        'image/x-png' => 'png'
                    );
    
    // GD Function List
    $gd_function_suffix = array( 
                        'image/pjpeg' => 'JPEG',
                        'image/jpeg' => 'JPEG',
                        'image/gif' => 'GIF',
                        'image/bmp' => 'WBMP',
                        'image/x-png' => 'PNG'
                    );

    // Fetch the photo array sent by preupload.php
    $photos_uploaded = $_FILES['photo_filename'];

    // Fetch the photo caption array
    $photo_caption = $_POST['photo_caption'];

    while( $counter <= count($photos_uploaded) )
    {
        if($photos_uploaded['size'][$counter] > 0)
        {
            if(!array_key_exists($photos_uploaded['type'][$counter], $known_photo_types))
            {
                $result_final .= "File ".($counter+1)." is not a photo
";
            }
            else
            {
                mysql_query( "INSERT INTO ".$db_prefix."gallery_photos(`photo_filename`, `photo_caption`, `photo_category`) VALUES('0', '".addslashes($photo_caption[$counter])."', '".addslashes($_POST['category'])."')" );
                $new_id = mysql_insert_id();
                $filetype = $photos_uploaded['type'][$counter];
                $extention = $known_photo_types[$filetype];
                $filename = $new_id.".".$extention;

                mysql_query( "UPDATE ".$db_prefix."gallery_photos SET photo_filename='".addslashes($img_prefix.$filename)."' WHERE photo_id='".addslashes($new_id)."'" );

                // Store the orignal file
                move_uploaded_file($photos_uploaded["tmp_name"][$counter], $images_dir."/".$img_prefix.$filename);

                // Let's get the Thumbnail size
                $size = GetImageSize( $images_dir."/".$img_prefix.$filename );
                if($size[0] > $size[1])
                {
                    $thumbnail_width = 160;
                    $thumbnail_height = (int)(160 * $size[1] / $size[0]);
                }
                else
                {
                    $thumbnail_width = (int)(120 * $size[0] / $size[1]);
                    $thumbnail_height = 120;
                }
            
                // Build Thumbnail with GD 1.x.x, you can use the other described methods too
                $function_suffix = $gd_function_suffix[$filetype];
                $function_to_read = "ImageCreateFrom".$function_suffix;
                $function_to_write = "Image".$function_suffix;

                // Read the source file
                $source_handle = $function_to_read ( $images_dir."/".$img_prefix.$filename ); 
                
                if($source_handle)
                {
                    // Let's create an blank image for the thumbnail
                         $destination_handle = Imagecreatetruecolor( $thumbnail_width, $thumbnail_height );
                
                    // Now we resize it
                      ImageCopyResampled ( $destination_handle, $source_handle, 0, 0, 0, 0, $thumbnail_width, $thumbnail_height, $size[0], $size[1] );
                }

                // Let's save the thumbnail
                $function_to_write( $destination_handle, $tb_images_dir."/tb_".$img_prefix.$filename );
                ImageDestroy($destination_handle );
                //

                $result_final .= "[img]".$tb_images_dir. "/tb_".$img_prefix.$filename."[/img] File ".($counter+1)." Added
";
            }
        }
    $counter++;
    }

    // Print Result
echo <<<__HTML_END

<html>
<head>
    <title>Photos uploaded</title>
</head>
<body>
    $result_final
</body>
</html>

__HTML_END;
?>