Salve a tutti!
Stavo inserendo Captcha in un form e mi dà un errore strano...
Ecco il segnale di errore:

Warning: session_start() [function.session-start]: Cannot send session cookie - headers already sent by (output started at /home/dmbandi/public_html/petition.php:215) in /home/dmbandi/public_html/petition.php on line 230

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/dmbandi/public_html/petition.php:215) in /home/dmbandi/public_html/petition.php on line 230

Warning: imagecreatefromjpeg(captcha.jpg) [function.imagecreatefromjpeg]: failed to open stream: No such file or directory in /home/dmbandi/public_html/petition.php on line 233

Warning: imagecolorallocate(): supplied argument is not a valid Image resource in /home/dmbandi/public_html/petition.php on line 234

Warning: imagestring(): supplied argument is not a valid Image resource in /home/dmbandi/public_html/petition.php on line 235

Warning: Cannot modify header information - headers already sent by (output started at /home/dmbandi/public_html/petition.php:215) in /home/dmbandi/public_html/petition.php on line 237

Warning: imagejpeg(): supplied argument is not a valid Image resource in /home/dmbandi/public_html/petition.php on line 238


Ed ecco lo script dalla riga 230:
Codice PHP:
 session_start();
    $stringa = md5(microtime());
    $risultato = substr($stringa, 0, 5);
    $immagine = imagecreatefromjpeg("captcha.jpg");
    $testo = imagecolorallocate($immagine, 255, 255, 255);
    imagestring($immagine, 3, 20, 10, $risultato, $testo);
    $_SESSION['CONTROLLO'] = $risultato;
    header("Content-type: image/jpeg");
    imagejpeg($immagine);