Consider a PHP Class with the following constructor:

public function __construct() {
    $this->connection = mysql_connect($this->server,  $this->username,  $this->password);

    if(mysql_error()) {
        $msg = mysql_errno() . ": " . mysql_error();
        throw new Exception('MySQL Error - '. $msg);
    }

    mysql_select_db($this->databasename);
}

when an exception is thrown, Zend AMF ignores it and throws an exception with the message "Error instantiating class"

            try {
                $object = $info->getDeclaringClass()->newInstance();
            } catch (Exception $e) {
                require_once 'Zend/Amf/Server/Exception.php';
                throw new Zend_Amf_Server_Exception('Error instantiating class ' . $class . ' to invoke method ' . $info->getName(), 621);
            }

While throwing this exception, ZendAMF should append the error message from the caught exception.