Error 400 creating Paypal Billing Plan:

I am creating a paypal payment system with Laravel 5.4. Direct payments work perfectly, but when creating a "BillingPlan" to make recurring payments I get this answer

Got Http response code 400 when accessing link

My code:

$plan = new Plan();

    $plan->setName('T-Shirt of the Month Club Plan')
        ->setDescription('Template creation.')
        ->setType('fixed');

    $paymentDefinition = new PaymentDefinition();

    $paymentDefinition->setName('Regular Payments')
        ->setType('REGULAR')
        ->setFrequency('Year')
        ->setFrequencyInterval("1")
        ->setCycles("20")
        ->setAmount(new Currency(array('value' => 100, 'currency' => 'USD')));

    $chargeModel = new ChargeModel();
    $chargeModel->setType('TAX')
        ->setAmount(new Currency(array('value' => 0, 'currency' => 'USD')));

    $paymentDefinition->setChargeModels(array($chargeModel));

    $merchantPreferences = new MerchantPreferences();

    $merchantPreferences
        ->setReturnUrl(url('get_agreement'))
        ->setCancelUrl(url('get_agreement'))
        ->setNotifyUrl(url('get_agreement'))
        ->setAutoBillAmount("yes")
        ->setInitialFailAmountAction("CONTINUE")
        ->setMaxFailAttempts("0")
        ->setSetupFee(new Currency(array('value' => 1, 'currency' => 'USD')));

    $plan->setPaymentDefinitions(array($paymentDefinition));
    $plan->setMerchantPreferences($merchantPreferences);

    $request = clone $plan;

    try {
        $output = $plan->create($apiContext);
    } catch (Exception $ex) {

    }



    return $output;

Json Response:

{"name":"T-Shirt of the Month Club Plan","description":"Template creation.","type":"fixed","payment_definitions":[{"name":"Regular Payments","type":"REGULAR","frequency":"Year","frequency_interval":"1","cycles":"20","amount":{"value":"100","currency":"USD"},"charge_models":[{"type":"TAX","amount":{"value":"0","currency":"USD"}}]}],"merchant_preferences":{"return_url":"http://localhost/paypalReceiver/public/get_agreement","cancel_url":"http://localhost/paypalReceiver/public/get_agreement","notify_url":"http://localhost/paypalReceiver/public/get_agreement","auto_bill_amount":"yes","initial_fail_amount_action":"CONTINUE","max_fail_attempts":"0","setup_fee":{"value":"1","currency":"USD"}}}