I am getting error 500 - php

Question

I am working on a site where people can get a bitcoin adres. When I do the GET request to the file, it gives a response of HTTP error 500. But I can't find any wrong things. Her is my script:
<?php
ob_start();
session_start();
error_reporting(0);
include("../includes/config.php");
$db = new mysqli($CONF['host'], $CONF['user'], $CONF['pass'], $CONF['name']);
if ($db->connect_errno) {
echo "Failed to connect to MySQL: (" . $db->connect_errno . ") " . $db->connect_error;
}
$db->set_charset("utf8");
$settingsQuery = $db->query("SELECT * FROM btc_settings ORDER BY id DESC LIMIT 1");
$settings = $settingsQuery->fetch_assoc();
include("../includes/block_io.php");
include("../includes/functions.php");
//include(getLanguage($settings['url'],null,2));
if(checkSession()) {
$type = protect($_GET['type']);
if($type == "receive") {
} elseif($type == "new_address") {
$nums = $db->query("SELECT * FROM btc_users_addresses WHERE uid='".$_SESSION['btc_uid']."'");
if($nums->num_rows > $settings['max_addresses_per_account']) {
$data['status'] = 'error';
$data['msg'] = error("You've reached the limit of wallet addresses. Max: $settings[max_addresses_per_account]");
} else {
$label = protect($_POST['label']);
if(!empty($label) && !isValidUsername($label)) { $data['status'] = 'error'; $data['msg'] = error("Please enter valid label. Use only characters and symbols - and _."); }
else {
if(empty($label)) { $label = randomHash(7); }
$username = idinfo($_SESSION['btc_uid'],"username");
$generate_address = btc_generate_address($username,$label);
if($generate_address) {
$data['status'] = 'success';
$data['msg'] = success("Your new address is <b>" . $generate_address . "</b>.");
} else {
$data['status'] = 'error';
$data['msg'] = error("Error with creating address. Please try again.");
}
}
}
echo json_encode($data);
} elseif($type == "send_bitcoins") {
$address = protect($_GET['from_address']);
$to_address = protect($_POST['to_address']);
$amount = protect($_POST['amount']);
$secret_pin = protect($_POST['secret_pin']);
$secret_pin = md5($secret_pin);
$check = $db->query("SELECT * FROM btc_users_addresses WHERE uid='".$_SESSION[btc_uid]."' and address='$address'");
if($check->num_rows==0) {
$data['status'] = 'error';
$data['msg'] = error("This wallet address is not yours!");
} elseif(empty($address) or empty($to_address) or empty($amount)) {
$data['status'] = 'error';
$data['msg'] = error("All fields are required.");
} elseif(!is_numeric($amount)) {
$data['status'] = 'error';
$data['msg'] = error("Please enter Bitcoin amount with numbers. Format: 0.000000");
} elseif(idinfo($_SESSION['btc_uid'],"secret_pin") && idinfo($_SESSION['btc_uid'],"secret_pin") !== $secret_pin) {
$data['status'] = 'error';
$data['msg'] = error("Wrong Secret PIN!");
} else {
$row = $check->fetch_assoc();
$total = $row['available_balance'];
$total = $total - 0.0008;
$total = $total - $settings['withdrawal_comission'];
if($total < 0) { $total = '0.0000'; }
if($amount > $total) {
$data['status'] = 'error';
$data['msg'] = error("Total available minus fees <b>" . $total . "</b> BTC.");
} else {
$newamount = $row['available_balance']-$amount;
$newamount = $newamount - 0.0008 - $settings['withdrawal_comission'];
$license_query = $db->query("SELECT * FROM btc_blockio_licenses WHERE id='".$row[lid]."' ORDER BY id");
$license = $license_query->fetch_assoc();
$apiKey = $license['license'];
$pin = $license['secret_pin'];
$version = 2; // the API version
$block_io = new BlockIo($apiKey, $pin, $version);
$withdrawal = $block_io->withdraw_from_addresses(array('amounts' => $amount, 'from_addresses' => $address, 'to_addresses' => $to_address));
$withdrawal = $block_io->withdraw_from_addresses(array('amounts' => $settings[withdrawal_comission], 'from_addresses' => $address, 'to_addresses' => $license[address]));
$data['status'] = 'success';
$data['msg'] = success("You sent <b>" . $amount . "</b> BTC to <b>" . $to_address . "</b> successfully.");
$data['btc_total'] = $newamount;
}
}
echo json_encode($data);
} elseif($type == "receive_to_address") {
} elseif($type == "archive_address") {
$address_id = protect($_GET['address_id']);
$query = $db->query("SELECT * FROM btc_users_addresses WHERE uid='".$_SESSION[btc_uid]."' and id='".$address_id."'");
if($query->num_rows>0) {
$row = $query->fetch_assoc();
if($row['archived'] == "1") {
echo 'Your wallet address <b>'.$row[address].'</b> is already archived.';
} else {
$update = $db->query("UPDATE btc_users_addresses SET archived='1' WHERE id='".$row[id]."'");
echo 'Your wallet address <b>'.$row[address].'</b> was archived.';
}
} else {
echo 'This wallet address is not yours!';
}
} elseif($type == "unarchive_address") {
$address_id = protect($_GET['address_id']);
$query = $db->query("SELECT * FROM btc_users_addresses WHERE uid='".$_SESSION[btc_uid]."' and id='".$address_id."'");
if($query->num_rows>0) {
$row = $query->fetch_assoc();
if($row['archived'] == "0") {
echo 'Your wallet address <b>'.$row[address].'</b> is already unarchived.';
} else {
$update = $db->query("UPDATE btc_users_addresses SET archived='0' WHERE id='".$row[id]."'");
echo 'Your wallet address <b>'.$row[address].'</b> was unarchived.';
}
} else {
echo 'This wallet address is not yours!';
}
} else { }
}
?>
Thank you for helping me out! It must to give the address back...