Shiping api ups .. it show exception that this shipment/referenumber is not allowed for this shipment (120541).

Hello below is my code and i face issue while creating shipping label , please do guide me

The error is : Notice: Undefined variable: return in /home/ocanalytica/public_html/ups/ups-test/check.php on line 92

Notice: Undefined variable: return in /home/ocanalytica/public_html/ups/ups-test/check.php on line 162
errorobject(Ups\Exception\InvalidResponseException)#52 (7) { ["message":protected]=> string(75) "Failure: Shipment/ReferenceNumber is not allowed for this shipment (120541)" ["string":"Exception":private]=> string(0) "" ["code":protected]=> int(120541) ["file":protected]=> string(89) "/home/ocanalytica/public_html/ups/ups-test/UPS/vendor/gabrielbull/ups-api/src/Request.php" ["line":protected]=> int(145) ["trace":"Exception":private]=> array(2) { [0]=> array(6) { ["file"]=> string(90) "/home/ocanalytica/public_html/ups/ups-test/UPS/vendor/gabrielbull/ups-api/src/Shipping.php" ["line"]=> int(81) .............

My code is :
$accessKey = '*******';
$userId = '';
$password = '786@Ups';

// Start shipment
$shipment = new Ups\Entity\Shipment;

// Set shipper
$shipper = $shipment->getShipper();
$shipper->setShipperNumber('69R237');
$shipper->setName('Profiix');
$shipper->setAttentionName('Umer');
$shipperAddress = $shipper->getAddress();
$shipperAddress->setAddressLine1('11709 South Orange Blossom Trail');
$shipperAddress->setPostalCode('32837');
$shipperAddress->setCity('Orlando');
$shipperAddress->setStateProvinceCode('FL'); // required in US
$shipperAddress->setCountryCode('US');
$shipper->setAddress($shipperAddress);
$shipper->setEmailAddress('umer.shahzad.softwareengineer@gmail.com');
$shipper->setPhoneNumber('16092142857');
$shipment->setShipper($shipper);

// To address
$address = new \Ups\Entity\Address();
$address->setAddressLine1('591 Grand Avenue');
$address->setPostalCode('92069');
$address->setCity('San Marcos');
$address->setStateProvinceCode('CA'); // Required in US
$address->setCountryCode('US');
$shipTo = new \Ups\Entity\ShipTo();
$shipTo->setAddress($address);
$shipTo->setCompanyName('profiix');
$shipTo->setAttentionName('profiix Franchise');
$shipTo->setEmailAddress('umer.shahzad.softwareengineer@gmail.com');
//$shipTo->setPhoneNumber('');
$shipment->setShipTo($shipTo);

// From address
$address = new \Ups\Entity\Address();
$address->setAddressLine1('11709 S Orange Blossom Trail #106');
$address->setPostalCode('32837');
$address->setCity('Orlando');
$address->setStateProvinceCode('FL');
$address->setCountryCode('US');
$shipFrom = new \Ups\Entity\ShipFrom();
$shipFrom->setAddress($address);
$shipFrom->setName('Umer Shahzad');
$shipFrom->setAttentionName($shipFrom->getName());
$shipFrom->setCompanyName($shipFrom->getName());
$shipFrom->setEmailAddress('umer.shahzad@ocanalytica.com');
$shipFrom->setPhoneNumber('16092142857');
$shipment->setShipFrom($shipFrom);

/*
// Sold to
$address = new \Ups\Entity\Address();
$address->setAddressLine1('4002 Promenade Square Dr');
$address->setPostalCode('32837');
$address->setCity('Orlando');
$address->setCountryCode('US');
$address->setStateProvinceCode('FL');
$soldTo = new \Ups\Entity\SoldTo;
$soldTo->setAddress($address);
$soldTo->setAttentionName('Pro');
$soldTo->setCompanyName($soldTo->getAttentionName());
$soldTo->setEmailAddress('a.kungfu.man.umer@gmail.com');
$soldTo->setPhoneNumber('16092142857');
$shipment->setSoldTo($soldTo);
*/

// Set service
$service = new \Ups\Entity\Service;
$service->setCode(\Ups\Entity\Service::S_STANDARD);
$service->setDescription($service->getName());
$shipment->setService($service);

//$return ='';

// Mark as a return (if return)
if ($return) {
$returnService = new \Ups\Entity\ReturnService;
$returnService->setCode(\Ups\Entity\ReturnService::PRINT_RETURN_LABEL_PRL);
$shipment->setReturnService($returnService);
}

// Set description
$shipment->setDescription('For testing');

/*
// Add Package
$package = new \Ups\Entity\Package();
$package->getPackagingType()->setCode(\Ups\Entity\PackagingType::PT_PACKAGE);
$package->getPackageWeight()->setWeight(1);
$unit = new \Ups\Entity\UnitOfMeasurement;
$unit->setCode(\Ups\Entity\UnitOfMeasurement::UOM_KGS);
$package->getPackageWeight()->setUnitOfMeasurement($unit);

// Set Package Service Options
$packageServiceOptions = new \Ups\Entity\PackageServiceOptions();
$packageServiceOptions->setShipperReleaseIndicator(true);
$package->setPackageServiceOptions($packageServiceOptions);

// Set dimensions
$dimensions = new \Ups\Entity\Dimensions();
$dimensions->setHeight(1);
$dimensions->setWidth(1);
$dimensions->setLength(1);
$unit = new \Ups\Entity\UnitOfMeasurement;
$unit->setCode(\Ups\Entity\UnitOfMeasurement::UOM_IN);
$dimensions->setUnitOfMeasurement($unit);
$package->setDimensions($dimensions);
*/
// Add Package
$package = new \Ups\Entity\Package();
$package->getPackagingType()->setCode(\Ups\Entity\PackagingType::PT_PACKAGE);
$package->getPackageWeight()->setWeight(10);
$unit = new \Ups\Entity\UnitOfMeasurement;
$unit->setCode(\Ups\Entity\UnitOfMeasurement::UOM_KGS);
$package->getPackageWeight()->setUnitOfMeasurement($unit);

// Set Package Service Options
$packageServiceOptions = new \Ups\Entity\PackageServiceOptions();
$packageServiceOptions->setShipperReleaseIndicator(true);
$package->setPackageServiceOptions($packageServiceOptions);

// Set dimensions
$dimensions = new \Ups\Entity\Dimensions();
$dimensions->setHeight(10);
$dimensions->setWidth(10);
$dimensions->setLength(10);
$unit = new \Ups\Entity\UnitOfMeasurement;
$unit->setCode(\Ups\Entity\UnitOfMeasurement::UOM_CM);
$dimensions->setUnitOfMeasurement($unit);
$package->setDimensions($dimensions);

// Add descriptions because it is a package
$package->setDescription('Package weight');

// Add this package
$shipment->addPackage($package);

$order_id = '69R237';

// Set Reference Number
$referenceNumber = new \Ups\Entity\ReferenceNumber;
if ($return) {
$referenceNumber->setCode(\Ups\Entity\ ReferenceNumber::CODE_RETURN_AUTHORIZATION_NUMBER);
$referenceNumber->setValue($return_id);
} else {
$referenceNumber->setCode(\Ups\Entity\ReferenceNumber::CODE_INVOICE_NUMBER);
$referenceNumber->setValue($order_id);
}
$shipment->setReferenceNumber($referenceNumber);

// Set payment information
$shipment->setPaymentInformation(new \Ups\Entity\PaymentInformation('prepaid', (object)array('AccountNumber' => '69R237')));

// Ask for negotiated rates (optional)
$rateInformation = new \Ups\Entity\RateInformation;
$rateInformation->setNegotiatedRatesIndicator(1);
$shipment->setRateInformation($rateInformation);

// Get shipment info
try {
$api = new Ups\Shipping($accessKey, $userId, $password);

$confirm = $api->confirm(\Ups\Shipping::REQ_VALIDATE, $shipment);
var_dump($confirm); // Confirm holds the digest you need to accept the result

if ($confirm) {
$accept = $api->accept($confirm->ShipmentDigest);
var_dump($accept); // Accept holds the label and additional information
}
} catch (\Exception $e) {
echo "error";
var_dump($e);
}